Linux is better than Windows because it is open source and the backdoors and vulnerabilities are found fast and fixed fast unlike Windows that can take ages or never happen! but it is still not 100% safe as long as it is  connected to the internet and you still have to follow the security precautions.

first of all you should not have any coins or any valuable information for that matter on your hot computer that has access to the internet. it doesn't matter what you do, your data is at risk when you connect to internet.
secondly having AntiViruses are like the last defense to have on your computer. the first thing to do is prevention, as they say it is better than cure! it means you never visit shady sites, you never download and install any application that you don't know.

i was pointing out the "special cases" of each of these situations where they may become true
for example satoshi is right nodes can't tell these things but there is a way of isolating a node that you want (like government performing these stuff with a lot of funds) and get the information you want out of it.
read the replies to this: https://bitcointalk.org/index.php?topic=1581065.0;all

there are no cycles when you look deep in why the price moved the way it did at that particular time. there is almost always some reason for it and rarely it goes up and down without a reason.
for example you say February and April prices are almost the same, last year price was on the rise in February and would have been sitting at $2000 by April if it wasn't for the FUD. the reason why you see the drop there and you see the same price as February in April is because the drama about splitting bitcoin and killing it started and caused a lot of panic and the whales like always used it to manipulate hence the March 10 weird candle where orders were cleaned up in less than a minute and the weak hands always follow and crash the market.

altcoins are temporarily good for as long as they have existed. when people buy them they do it in order to make profit, usually on the bitcoin they have. also when bitcoin "dips" as we all know altcoins drop harder even so buying others means losing even more money. so why would you do that?

to be fair bitcoin is a currency (it is designed to be one) so it has merchant adoption. ethereum is NOT a currency, instead it is designed to be a token so it must not have any merchant adoption at all!
the usage of it is for smart contracts, now the question is which one of these thousands of smart contracts (ICOs) that have been created in the past couple of years have actually done something? the answer is 0. they all have been useless. they create some imaginary problem and then pretend to fix it.

nothing really. he basically creates a couple of topics each week all of which are focusing on some doomsday as he spreads some dumb bullshit around to make us laugh at his ass.
i think he is either kuwukduck himself or saw his post history and took lessons

you can't do it with 51% hash rate, you need a lot more. it is like an arm wrestling contest if you have 1% more power than your opponent you can beat him but it won't be easy because you are practically the same. they say 51% to say you need to have more than half the hashrate to begin. but the attack can be pulled off with a much higher hashrate. the higher the easier.

1) go to your console and get the list of all your addresses.
2) go here: http://www.findmycoins.ninja/ and paste the list here and separate them with a new line and remove any extra symbol that it might have (like " or ,) and click search
3) now from the results choose the ones that contain some fork_coin and copy the single address.
4) go back to electrum and get the private key of that address
enter your password if you have one and you will see your private key.
5) copy it and use it in any fork_coin wallet that you want and claim your reward.

it is best not to use this wallet anymore. move to a NEW wallet (not just a new address from the same wallet) create a new seed.

not at all. altcoin dumps were the main reason for bitcoin price drop.

what happens are two things. altcoins are naturally getting dumped since they are pump and dumps anyways. then there is also the  Coinrail hack which was mainly an altcoin exchange and the stolen funds were all altcoins. so the panic was in altcoin market where everyone started dumping their altcoins. that creates  a wave of money exiting the market. and guess where they choose to exit? bitcoin then they dump bitcoin for fiat also and crash bitcoin price too.

for the millionth time the 2013 bubble and bear market was not the first and only one that bitcoin experienced. i don't know why some people like the OP is quoting are so think in the head that they fail to figure this out on their own! 2013 thing was already 4th or 5th one that we had and it was the longest. before that we had even bigger bubbles and corrections but none of them lasted that long. so just taking one trend and making the decision based on that is foolish enough not to mention that history does not repeat when it comes to a dynamic market that is always changing.

i disagree. all the "good" investors know that it is the worst time to invest in cryptocurrencies because first of all bitcoin is going down so cryptocurrencies are going down harder and also with all the altcoin dumps you should never catch a falling knife!
additionally the situation has not "worsened" it was bad all along when they were pumping all these shitcoins but you didn't notice it only because you were caught up in the hype of the pump.

all i remember and your post history also shows is that you were always saying "remember i told you so" but you never said anything. i also remember you were saying you sold all your coins before price reached $10k and missed the 110% rise to $20k and then bought at the peak.
i also remember you were bag holding BTG and you were constantly getting dumped on and lost a lot of money in it

p.s. people laugh at you not be cause of the price you are telling them but because of the randomness of your guesses and the false confidence you have in your random guess...

there was a bug in the old Electrum version that you are using. this bug causes some issues when trying to parse certain transactions that are using SegWit. this problem was fixed a couple of months ago in release version 3.0.6
the way to fix this is to update to the latest version which is currently 3.1.3

you are making the two huge mistakes which are practically the biggest mistakes anyone can make.
first is listening to random idiots on the internet who are advertising the shitcoins they have been bag holding and want to get rid of.
and second is calling the bags you are bag holding as a "portfolio". this pretty word that they introduced to altcoin bag holders last year is used to mask the fact that they are making a big mistake by holding a lot of shitcoins and lose money in the process. altcoins are not meant to be held more than the duration of their pumps which can be from a couple of hours to a couple of days tops.

i honestly never understand how they can prove this kind of manipulation. we all know that it exists and  we have all seen it in different forms such as fake walls that are placed to create illusions of sell pressure or buy support. but they are real orders with real funds and there always is a plausible deniability to it, even if your history is filled with this kind of orders.
also i believe exchanges don't keep not-closed order history! so they may not even have a history of these walls that are never filled.

when it comes to altcoin market and all that is related to it, you  can not trust any website and anybody that ranks them and gives you suggestions because they will always be biased. most of the times they are getting paid to be biased. even the big famous news websites have done this in the past and are still doing it from time to time because everyone loves to be paid. but also sometimes they are not paid to do it but they have a big stake in what they are advertising and if some newbies fall for their advertisement and buy into it then they will make profit!

here is the closest visualization of this that i could find:
it shows 2.439 (~2.44) MB of transactions paying 200, 199,198,...,20,19,...,10,...,4 satoshi/byte fees. and when a block is found it can only contain a little more than 1 MB of those and miners will prefer the higher paying transactions. so you have about 2.44 MB in front of you.

"can be" is very different from "is". a lot of things can be a lot of things but they aren't. ICOs are one of them. and since so far not even one ICO has been remotely good you can say that this lifting of the ban is the strangest thing that they could have done! in a world where everyone is banning ICOs and preventing them from scamming people taking a step back is like undoing all the things you have done so far.

your title and your poll are asking two different questions though. finding out whether someone has bitcoin or not can be a little different than finding how much and which coins.
for example when someone talks about bitcoin all the time, visits bitcoin related websites (bitcointalk, coinbase,...), has a bitcoin wallet installed then it is a safe assumption that they own bitcoin.
but knowing which address belongs to you and how much bitcoin you own is a much harder thing.

in any case multiple choices of that poll can be correct.

• Yes - it is pseudo anonymous so if you are not careful it can be revealed is the most obvious answer.
  
• Yes - through GPS in the bitcoin wallet code can be correct if you are using some unknown wallet that may have a backdoor not that there is any that i have seen so far!
  
• Yes - your identity is always revealed this depends on the type of wallet you are using. if you are using a WALLET like bitcoin core, armory, electrum,... then it is not. but if you are using a bitcoin ACCOUNT which they call wallet such as  coinbase then it is true.
  
• Yes - through the nodes this can also be true but not easy. basically you have to create a ton of nodes and connect to a ton of other nodes. then you select someone's node and connect to it and fill all its connection slots. each time that node sends a transaction you check to see whether you have seen this transaction before (if it is relaying it) or it is a new one (creating it). if it is new then he owns the coins.