NISA for someone financially illiterate

So I have just let my money sit in a bank account my whole life, big waste I know. I just hate the stress of any kind of gambling or risks with money involved, and hate any kind of tax related issues. I freelance and run my own thing as a sole proprietorship, but I have a tax guy that handles the yearly tax work.

I thought it was time though and I have now signed up for the Rakuten NISA/trading account and their credit card, seems like it was approved.

I have gone trough a lot of posts in here regarding NISA, but I feel that even though a lot of it was for beginners I might be at an even lower level than that, so if someone possibly have the time, I have some questions.

1. I have read that mutual funds are probably best type if I'm looking for something low risk, but what is the actual name I should be looking for?

2. I know NISA itself comes with some kind of tax benefits, I'm guessing that is for when you actually start to take out money? Is there anything I have to declare when I'm just putting money in? or while it being invested?

3. If I were to come into economic troubles how fast would I actually be able to get my money out off it and in to my regular bank account? If I for example had my money in a mutual fund, or what ever it might be called.

4. What happens with a NISA account if I were for example happen to leave Japan? Would I need to shut it down?

5. I saw someone mention that there were two types of trading accounts for NISA both with their own limits for each year. I doubt I will put in more than 100万 a year, so don't think I'll hit any limits on either, but in that case which one should I use? or split between them?

Thanks in advance.