centenial wrote:
Is there a way to pass 'additional' information to PayPal? (for example, a 'username' or 'password' that the customer filled out before clicking the 'add to cart' button?)
No, but you can send an order ID which will be returned to you via PDT and/or IPN upon successful completion of the payment.
You could store this additional info against the order ID and release it upon receipt of payment.
I've heard of something called PayPal IPN.... would that do it?
No, that's not what it does.
IPN sends a message back to your web site upon successful completion of the payment (and refunds).
You can use this to mark the order as paid. In the case of products delivered electronically, you could use this to fulfil the order to.
Mark