Questions from a beginner

Hello, all. I'm just starting into crypto mining, and although I tried to search for information, it's all very complicated, and there are so many different coins and whatnot, that I couldn't find the answer (or understand the information) to some of my questions.

I think these must be very basic stuff, but I would really appreciate if someone could take the time to answer them.

1 – What happens to my wallet if my PC breaks/gets stolen? I wrote down the 12 words, and I would guess this is used to recover the wallet, but I guess I would also need something like "wallet address"? When I created an Ethereum account on MetaMask it gave me an address in addition to the 12 words. However, on Raven Core, it didn't give me anything, and the only address I have is a "receiving address" I had to manually create, and the program itself says "it is recommended to use a new receiving address for each transaction", meaning a wallet may have countless receiving addresses. So when (and if) I want to recover my wallet, what information exactly would I need other than the 12 words?

I remember an episode of Big Bang Theory where they lost a pendrive in which the wallet was, and all their coins were gone. This is my biggest fear in dealing with crypto – a coin I bet on suddenly rising, and I see I lost access to the wallet.

2 – I've seen sites saying Ravencoin is one of the best coins to mine now, and it's why I decided to try it. However, I saw its value was over $0.20 a little while ago, and now it sits at $0.07 for the last few weeks. Isn't this a bad sign?

3 – Although I think it's really improbable that any coin will reach Bitcoin's value, Ethereum's value is now more than $2,000 per coin. Is there a chance Ravencoin may reach the same value as Ethereum?

4 – My plan right now is to mine for a few weeks (maybe a couple of months?) and stop to not break my brand new GPU (I fear the GPU – a 3090 – cost me more than I will ever make with crypto currency), and after that hold the coins for a few years in hope of its value getting high, then selling them. Is it a reasonable idea?

5 – I'm using Bitflyer, but there isn't an option for Ravencoin there. Does this mean I can't sell my coins through them? I see many people use Binance, but from a quick search, it seems using Japanese bank or card hardly ever works there.

That is all for now. I'm sorry if these seem like noob questions.