hello, i am a new seller on amazon and i would like some help from you guys, please. where can i get a manufacturer in the United States? How do i know what products to sell?

I have some questions, and I would love to get answered by some experts please.

1- How long does it take to get first sale organically for a new fba listing (estimated)?

2- I am doing retail arbitrage, and First product I tested were three units, I sent them to fba, and got 2 sales with ppc and got the last 1 sale organically, is there a sign that it is a good product and should I test it again with larger quantity?

3- Currently I am selling Iphone cases, I sent 50 units, and I run ppc campaigns including manual and auto, getting high impression and low clicks, and literally no sales, what should I do? I optimized the title, description, bullet point very well with keywords. Should I stop running campaigns and wait for it to rank organically?

Hello. I need a proof of delivery for fba shipment older than 120 days. I know for first option is contact a carrier but it slowly. Anyone have other method for this?. Can I track with FBA shipment ID? or anything