Things I would be aware of is when you are put in the queue (after clicking register link on runDisney), that page will refresh on its own & there is no countdown. These are both normal. Check your profile under manage account now to make sure it's correct. Double check auto fill doesn't change anything as you go when registering and on the payment page. Some people did get pending charge(s) for registration(s) that didn't go through for whatever reason. Those should drop off as they are pending. So, they weren't getting the confirmation page, nothing in their manage account dashboard and no email (emails could come slow). So, basically it was if you don't get a confirmation (check on your dashboard or email) you had to re-register. I'm sure IT is working hard to correct issues for Princess. Have patience & pixie dust as waits to get in may be slower to avoid issues I would think maybe.
Oh, and also it's only ONE form of payment (one gift card, credit card or Rewards Chase card). You can combine gift cards on Disney Gift Card site. You can use Debit card but personally I would avoid Debit if possible with the issues yesterday.