Amazon Ungate FAQ

It's against Amazon's terms of service to buy products on Prime for the purpose of reselling. You risk getting both your customer and seller accounts banned.
Returning ungates bought anywhere risks getting your seller account deactivated. There's a small chance Amazon will go back to the distributor to verify you didn't return them. It also potentially burns the bridge for future sellers. Distributors who get enough 10 quantity orders and returns will simply limit order quantities. List them back on Amazon and take the loss. It's a tax write off so it's eventually break even, and if you pick a cheap enough product, the loss will be minimal.
Ungating one brand in the category ungates the entire category, but sometimes other brands need separate ungating in the category.
Open a new Amazon account, individual or business, and don't subscribe to Prime.
Go to Your Orders. On the order, click either the Print Invoice link or Printable Order Summary. Print to PDF.
The account holders on both accounts must be the same, and the addresses must both match. So that's fine as long as both account holders and the addresses match. For example, using a friend's amazon account to buy 10 units and ungating on a seller account in your name will not work.
Yes in most cases. Sometimes Amazon will reject new sellers due to not having enough seller history on a case by case basis. If push comes to shove, return the items to Amazon. Either try a different brand, or try again in 30 days after selling products.