you are confusing the "implementation bug" with "protocol bug" and they are very different. Bitcoin was and is still is flawless but the all the implementations are filled with flaws. to this day we still find new bugs and from time to time we even introduce new bugs in our software. that is inevitable.
here are the two recent examples of serious bugs that were found in two different implementations of bitcoin: 1 and 2 but neither of these mean bitcoin is flawed!

address is not exactly public key, and you don't need to store your public key. i don't want to confuse you with the technical background of bitcoin (i can explain more if you like) but know that public key is the public part of the "key pair" that is safe to share but you don't need to do that. it is derived from private key then it is hashed and then it is encoded so that you see a human readable string which you call your address.
all you need to store is your private key (keep secret) and your address (can share so that you can receive bitcoin)

as for "p2pkh:" it is specific to Electrum, it is telling you what type of address your private key links to. as long as you are also storing your address, you should know this and even if it was unclear from address (like if it was starting with 3) or if you didn't have your address anymore you could still derive all possible addresses from your private key and see which one is the correct one.
by the way"p2pkh:" is saying it is a "Pay To Pubkey Hash" or in other words you have an address that starts with `1`

the "correct" way is ALWAYS to move the coins also known as sweeping whenever you want  to change wallets for many reasons including security

i am assuming you are using the latest version, if you are using a version between 3.0 and 3.0.6, this answer is invalid due to the usage of versioned private keys which need to be converted first (upgrading to latest version takes care of that)

go to your address tab and select the address you want to transfer, right click on it and select Private Key. (if you have password it will be required) a new window will show up showing you the private key which will be in form of type:key
in your case it will be p2wpkh:<privatekey> so just copy the <privatekey> part and import that in your core wallet.

i am not familiar with core that much but i believe in there you don't have the option to tell the wallet the address type! so it checks all the possible addresses!

i honestly haven't seen any of these (apart from 2 or 3 of them) ever be used as bitcoin symbol so i am going to be skeptical. could you also add where you got each of these symbols from so that they don't look like random pictures some random person thought of on the internet?

also there are repeated symbols, you may want to categorize them under one. for instance https://satoshisymbol.yolasite.com/resources/greeniscolor.jpg is repeated 3 times just with a different color.

the pictures are mostly simulation rather than the real product so you can't really say that. they don't have any scale either so it is impossible to tell. i did some search and i couldn't find the dimensions of it anywhere! you have wait for its release and check the seller's website, they usually include those things.

we have been out of the bear market ever since price started its reversal a couple of months ago. people fail to see it because they think end of a bear market should start with a big ass rise to the moon! but in reality end of a bear market is a trend transition which takes time and starts with accumulation.

they are nowhere near ATH because of the massive spam attack that we had in 2017 it has manipulated ATH so there is no way we can easily get there.
it is one of many proofs of adoption though. not the best one.

the only issues with sharing the xpub that i am aware of are
- privacy issue, which is obvious since anybody having the xpub can get all the addresses that belongs to that user.
- security issue which is only when non-hardened paths are used and 1 and only 1 private key is leaked. the attacker can easily find the master private key by having that 1 private key and the extended public key.

apart from that xpub is just as safe as public keys.

i don't know about copay but Electrum is one of the rare wallets that uses non-hardened paths which is why you can use the master public key to derive the child keys. if you want to find out more about how these things work then read BIP32: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki

there is another option for wallets that use a hardened path which is deriving the child extended public key and then importing that but setting the derivation path after than to m/0, m/1, ...
for example if a wallet uses the path m/0'/44'/2' and each key comes from m/0'/44'/2'/0 and m/0'/44'/2'/1 and so on then the user can get the extended public key from the master private key at m/0'/44'/2' and then uses that to get the child public keys by extending them one level (meaning add the /0, /1,...).

obviously this wouldn't work if the keys are also hardened (m/0'/44'/2'/0', m/0'/44'/2'/1',...).

you can play around with the concept here: https://iancoleman.io/bip39/ generate a random key and scroll down to "Derivation Path" and select BIP32 tab and set different derivation paths. you can copy the xpub in textbox above this part called "BIP32 Root Key" and see which one works and which ones don't.

why does "malware" keep coming up here? there is NO malware to be detected at least not in the alternate (fake) Electrums that i have seen so far. it is simply an addition of a couple of lines of code that spends your coins to a specific hardcoded address. that is not malware, that is simple wallet functionality like the functionality of the real wallet!
as soon as you enter your password, so that the fake wallet has access to the decrypted keys, it runs a simple code which looks like this:
you can't detect this with an antivirus! if your AV detected this then it should have also warned you every time you opened your real electrum!

it is somewhat pointless because of two things.
it lacks privacy and people have other better options such as running light wallets like Electrum and creating a watch only wallet there with their master public key.
it also wouldn't work for most wallets since nowadays they mostly use hardened paths which means you can't derive the child keys from a master public key!

P.S. you should move this to Project Development board, there is a button for it at the bottom left side of this page.

i simply have my seed written down on a piece of paper and that paper is stored safely among my belongings. i also have all of the passwords that i have used for encrypting important stuff (the live Linux on the USB and the Electrum wallet on it)  on paper and they are stored similarly. they don't yet know how to recover it but they are aware that i own bitcoin so it would be easy for them to simply figure it out.

i may add some sort of encryption on my seed and store the encrypted later and store the password separately to increase its security a little bit.

your title should have said "remarkable" instead of "surprising", i am surprised about a couple of annoying things these days but it doesn't seem to be what you are actually looking for here.

what i have always found remarkable in bitcoin is the technology, specifically the cryptography part of it. what it was and the fact that it still is improving by time is phenomenal. and it is all math! and it doesn't stop there either. bitcoin has opened up a lot of possibilities with all the alternative ways of using the technology that it introduced to us.

don't!
ICOs have always been a terrible idea and majority of them have been purely scams. you could simply categorize all of them in 2017 as high risk bets in a gambling game. now in 2019 that they are nearly dead and people have stopped making such bets, they are even worse which means the odds of you "winning" such bets are nearly zero.

i think the first thing that you need to discuss about is that why do you think bitcoin should even  disrupt anything in first place? for example imagine a fast food that opens up on the other side of the street with a better menu than the old one, this new one doesn't "disrupt" the old one, it has just added more fierce competition and if the old one is shitty it will be removed unless it stops sucking.
that is what bitcoin is, that alternative that was created because the fiat system was shitty and it is not about to replace it unless it continues to suck.
and remember that bitcoin is here to solve problems not cause any, if you see some problems, know that they existed before bitcoin. with bitcoin they only became more obvious.

as others said this is probably a bug in their system but also remember that sometimes website such as Coinmarketcap.com also try to manipulate things simply because they have gained a big popularity and majority of the people who keep checking CMC are newbies who can easily panic by seeing such numbers. they have done this with some altcoins in the past and maybe they were trying things out with bitcoin this time, suffice it to say that it did not work though.

the first and the most important thing to consider is trustworthiness! for example check the history of the exchange and see different feedbacks to find out whether they have scammed anyone before and if they did that means they will do it again so stay away from such exchanges. a good source for that is bitcointalk, use the search function on top right corner of the webpage and also look for their announcement topic.

when you find a trustworthy exchange they will automatically also have higher volume (liquidity) list lots of coins, have better security and better options,...

a 2x rise in one year is the smallest amount of rise that bitcoin can have! and it has always been like this. if you check the history you can see that apart from the time when bitcoin is recovering from a MASSIVE bubble that takes a long time, other times we always have at least 2x rise. so with that in mind you can bet your ass that price should at least be $7000 by the end of the year. and the thing with price rises after the big dump is that the reversal is similar to a bubble burst, it is slow at first but as we cross certain thresholds (possibly $5k this time) they speed up so we can see a shoot up to $9k and back to $10k by the end of the year. considering all the good news that has been coming out including Bakkt we can see how that is a strong possibility.

it is impossible to say and no there is no "psychological number" yet because those only come in when we actually reach the price multiple times and don't break it. so far we have only done that once and with only one try that doesn't become strong resistant!
right now the only thing "psychological" as i have said before is that uncertainty which is not changing with any kind of TA on the charts. and uncertainty means nobody knows whether price is going up or down which is why it doesn't move at all!

if you want a truly decentralized network independent of the internet then you first have to establish a network on a different spectrum and then be able to use it. right now in case of "ham radio" that you mentioned here, you are connecting to a centralized "server" and send your transaction to them and then that server sends your transaction to the bitcoin network that is nodes connecting to each other via the internet.

this is in no way decentralized in my opinion! the only way that this could be considered decentralized were if actual bitcoin nodes existed that had the ability to connect to each other using Radio Frequency and just like port (8333) on the internet we could set a frequency defined for bitcoin (maybe in ELF range) that they all use to communicate.

i believe downloading the blockchain from somewhere else like the torrent file stopped being faster a long time ago. now it can even be slower.
remember that you still have to verify the whole blockchain so the process is the same you just download it elsewhere instead of letting the node software download it itself.