New member looking for info on Seller/Vendor and specific product type

I’ve recently written a book that I’m self publishing through Amazon, and am trying to better understand the best route to take through Amazon’s product offering. I don’t plan to use KDP (the books are already fully printed and won’t be available on Kindle, and have special packaging/additional elements).

Amazon Seller + FBA seems like the right route to go, based on research I’ve done (vs. Amazon Vendor), but most articles and videos I find regarding Amazon Seller seem catered toward cases unlike mine (a first time product with an ISBN), so it is making me second guess my choice.

My main questions after all of this are: 1. Am I correct in assuming Amazon Seller + FBA is the right course of action, assuming I want to have some degree of price control but don’t want to personally be shipping things anywhere but to a fulfillment center? 2. When I try to create a product on Amazon Seller app, do I NEED a Brand Name or trademark, or can I proceed without? 3. When I attempt to add the product as an ISBN with a product number, Amazon Seller app doesn’t recognize the ISBN. I’m unsure if, beyond acquiring an ISBN through normal means with Bowker, I need to make Amazon aware of that ISBN’s existence.

Thanks for any insight folks might have