Beginner questions, I really appreciate any advice.

I’m just starting out and have some questions, I would really appreciate some answers.

Here’s my plan (feel free to tell me if it’s bad) I’m going to buy phone cases from a manufacturer on Alibaba. Then receive the inventory, and send it to Amazon for FBA as an individual seller. I have some questions.

Once I purchase these cases, do they become my product since I’m buying from manufacturers? Or am I simply reselling them?

Do they come with upcs on them?

If I make my store name something like Trek Tech, and Trek Tech is already a registered brand, is that illegal?

Any other legal issues you could see me running into, or additional advice?