You can use the same email address for both buyer and seller accounts. I do, it makes things easier.
Buyer accounts are rarely suspended. As you know, buyer is king on amazon so unless you really do some dishonest stuff when buying, you are safe.
Buyer and seller accounts appear to be run separately.
One thing to watch out is the use of credit cards on your buyer account that might be owned and used by other people on their seller accounts. If you do that for any reason, even a legitimate one, there is going to be a link formed and likely suspension of your seller account (and maybe theirs).
They are brother. You would be surprised how often. This may happen if you leave a product review on a product from the same category as you are selling on amz or if you open A-Z claim, post a negative feedback for someone who reports you.
You’re okay to create amazon business buyer account with separate email & phone number but one thing I want to add is that if you’re using that for reselling on amazon so make sure that you wouldn’t use amazon business prime, use simple Amazon business.
Its totally fine just use a different email and dont have 2 business accounts - you’re only allowed 1. I did this before and they caught me haha but nothing happened i jst was sent an email saying only 1 account allowed