Sherry, first, get the $99 out of your head. That was accurate in December (pre-purchase the CD online for 99, which was a bargain when the CD was 124.95 at DLR like it is at WDW) but not anymore.
Your outline of entering the parks and getting pix at the pumpkin is exactly right. They will give you your card then.
Later, you can use the same card, just hand it over before your pictures are taken. Or if you and your friends split up, the one without the card can get their own. Or if you leave a card in the room, you can get another. The cards are free. Having your pictures taken is free.
If you really really want a 5x7 print for almost $13, you could indeed order that at the parks. Go into a pp center (one on Main Street and one at the "beginning" of Greetings from California in DCA), and you can look at your pictures on the monitors there, and order them.
You can also order the CD, but it's just the plain pictures. So if you are a photoshop master or you just like plain pictures, then that would work for you.
But if you want the cute add-ons that you can see in many peoples' pictures (check out my sept and dec trip reports) then you'll need to order it online AFTER your trip. Create a photopass account, add your card ID numbers, edit them like crazy, and order the CD.
When you are with other people, if other people get their own cards but you want all pix on ONE CD, make SURE that those people give you their cards!!! All of them! If they keep their cards and open their own account, without intervention from the photopass people (which is done sometimes, not all the time) you will NOT be able to put them on one CD. So collect all cards to be sure they are on ONE account.
You have 30 days from the first picture to enter the card IDs onto your account, and 30 days after that to order the CD or pictures or whatever.
I edited the heck out of mine in December, b/c I know that my taste changes, and even if I didn't like an edit at that time, maybe when I'm 50 I will.
After you order it and get it, you can take the CD to your handydandy photo place and have prints made, or you can post them onto sites like shutterly and order prints from there, etc. MUCH cheaper than $12.95 for a 5x7.