a transaction that has an OP_RETURN output is not invalid, that particular output is not spendable (for obvious reasons) that is why the amount of it is set to zero otherwise you would be burning coins.
as for the size the 40 byte is a very old rule, nowadays the limit is 83 bytes.

what exactly is the point of this?
they aren't moving the coins to any centralized place (such as exchanges) for anyone to be able to block the coins. not to mention that these addresses could easily changed (the coins send to new address, maybe run through a mixer) specially now that it is publicly announced!

offer your artistic abilities to those who are involved with bitcoin like a bitcoin related business which might be looking for a designer maybe for their advertisements,... when you finish work for these type of customers you can demand bitcoin directly since they already have it.
otherwise if you have paintings and things like that which you want to sell as Og said bitcoin is just a currency, you can include it among the other currencies you accept for selling your stuff.

it was bound to happen because it was an illegal move by the reserve bank of India to put such an unfair restriction on their users accounts and their money. it is surprising that they could keep it up this long before the supreme court ruled against it.
i suppose the same thing is going to happen with any other bank in any other country which tries doing similar things since there has never been any such bans on bitcoin itself in any of these countries.

China has already accepted bitcoin and it has been legal for many years, i believe from back in 2011 up until now. there is still some areas that need regulations to put an end to the very long FUD about China and bitcoin laws that have been circulating the internet nearly as long as bitcoin existed.

that doesn't matter to day traders and maker newbie manipulators. all they focus on is the short term and the possible panic sell that they could create hence all the crash talk.
eventually the weak hands will run out and this "dip" period would simply end which is when the rise begins like all the previous times. then it puts an end to the "crash talk" and starts a new talk about "have i missed the chance to buy?"!

you are wrong about both of them.
it all depends on the person, the situation and what skills they have. for example someone without any knowledge or skills doesn't have anything to offer as a freelancer so they end up doing meaningless jobs that pay them practically nothing. you can't conclude based on that!
same with trading. people who have no experience will always end up losing money.

on the other hand those who spend time gaining the knowledge first and then use that to gain experience will always end up succeeding in anything they enter.

sometimes there is an indirect effect but that would only be for a short amount of time.
it happens whenever bitcoin has been rising for a long time and it starts constantly being in the media. like during 2017. the effect is that whenever bitcoin is hyped up like this and is being advertised everywhere a lot of "newbies" come in which are going to be scammed by the new tokens so these shitcoins rise during those times.

i don't think so.
i remember a couple of years ago, i think it was in early 2017, the bitcoin price over at India started growing due to an ever increasing demand in that continent. it was so big that the difference grew as big as 40%. but that rise never had any major effects on bitcoin price in other markets (the USD value for instance). which makes me believe that this time it won't have any major effects either.

but there is a big difference here. when someone controls majority of a coin like steem they can control everything from transactions to forks and code changes since they have full control but in bitcoin even if someone had a very large percentage of the hashrate they still can't control the network. all they could do is mine empty blocks to create a big backlog otherwise if they make any changes it will be rejected by the entire network.

today i saw some articles here and there talking about a new "recession" caused by this virus outbreak which i think is mainly because the number of infected victims is growing fast in USA and also the US stock market has been responding with a lot of panic and then dumps.

if the recession happens then we may start seeing a big bitcoin adoption and a massive price rise that we have never seen before. i am thinking $1 million.

to be honest any rise even if it were big in the near future is not surprising at all, it is like last year near the same time when bitcoin was around $3k and people were surprised about the well expected rise past $4k and the follow up FOMO that brought bitcoin up to $8k before a correction happened. we are in the same situation now too so we can't really be surprised to see another development towards the new ATH this year.

i think part of the problem with some of the victims that boast the amount of money they have publicly is that they came to that money in a short time with little to no effort so they don't know how to deal with it. otherwise usually people who have earned their wealth through blood sweat and tears protect it a lot better and boast about it a lot less specially not in public.

and do you have any reason why you think that an 11 year long trend of rising in the same way (big percentages within short amount of time) is going to be changed this year and not just a small change a big change to small rise in a very long time?
because i don't see any reason at all for this trend to change. in fact i could see this trend become even stronger meaning much bigger rises in much shorter time frames like 1500% rise in a year instead of 1000% in 2 years.

there is nothing to see except some shitty website linking a medium post/joke from 11 months ago!

and yeah it is funny until they actually scam some people like they did in 2017 by lying about this company and that bank and those personalities were involved in their altcoin or in their ICO just to scam people!

then you have to look into how this type of addresses are created (https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses) and also the encoding used in them (https://en.bitcoin.it/wiki/Base58Check_encoding). going in reverse won't answer your questions.
in short the checksum is calculated by taking the 21 bytes input (version + result of HASH160) and performing 2 times SHA256 on it then taking the first 4 bytes.

i don't think there is any SPV ethereum clients. the ethereum nodes are somewhere between SPV and full node, a better term to describe them would be "half assed nodes" since they only download and verify a very tiny portion of the blockchain (about 1%) whereas in a SPV client you download the entire blockchain headers and merkle trees and verify them. for example Electrum clients currently store 619,838 block headers that is equal to the same number of block headers. they don't even do that in an etherum node, the history could be anything and they as a "half assed node" would never know it.

they have already done that! just search the keyword (bitcoin price rise + coronavirus) and you will find the articles that were linking the rise right before this drop to the spread of this virus around the world.

somewhere between 1 and 31^58 (31 because the longest bitcoin address in base58 can be 35 characters and you fixed the first 4 characters).
if you also fix the checksum which is i believe a little less than 5 characters then the number shrinks by a lot but still can be more than just one since it is a 4 byte collision with only a couple of initial bytes of the data set.

any particular reason you are asking this?

nowadays any newbie who buys some bitcoin considered themselves as "traders" and "experts" then start making statements where shitty news sites desperately publish as analysis.
this one in particular is the worst of them all! it could have made some sense if he was expecting a small rise due to the Coronavirus but it makes zero sense to expect such an enormous rise because of such an irrelevant thing!