1: A payment form, so that I can tell my customer that they should pay me x amount. I send them to a page on my web site. They enter their name, address, email address, invoice number/ref number, and the amount. They click and go to the paypal payment and all the info they put in the form gets passed to me once the payment is complete.
2: Similar to above, but I have an option on my web site to purchase a directory listing. I have a pay now button for one option, but it doesn't pass all the info, as above, to me once the payment is paid. So I have to contact the purchaser to get the info I need. There are three options, although I may want more (payment for a B&B listing, that sort of thing), and would need to list the info I need from each to be passed back to me once payment is made.