Chuck ---
You are correct in that I can't find any "rules" either. Do you ask the question as a buyer, seller or both? As a buyer, you are basically correct. When there's an offering, read all the comments, ask questions and only then seriously commit to buy.
Payment is usually made by PayPal or Google to the GB seller. Then you wait for sufficient orders and shipping.
HMike
and yes, Rob is correct to ask Scopeguy20 or other sellers. Glenn (Scopeguy20) will help you.