We just booked last week. This is how it went (and this has been the same for us on other trips as well).
After we called and did our reservations, within a week you should recieve a yellow letter in the mail. That letter will have your confirmation with a complete list of everything you have.
It will give you the total cost, the deposit amount, and the remainder to pay with a date you must pay by.
On the back are instructions if you wish to send in a check (there should be a return envelope in the letter with it), or just call them back and bill it to a credit card.
You will not get any more letters from them. They will not "remind" you to pay again.
When I called back last year and put the remainder of the cost on the CC, we did not get another letter saying we paid in full. They only time you will get another letter is if you change the reservations that change the price of your package (like adding Silver or Gold) or adding/remove days of the resort.
Also, I was told that they no longer will be sending out PS/Tour/Special events confirmation letters. I don't know how true that is, but I did set up 3 tours, and did not receive any confirmation letters. Last year I did get letter within a week on the tours. So I'm believing that this new policy is now in effect.
But the old way still works, when in question, call them.
Hope that helps...