No, you do not need a new phone from Tracfone. You need a new
SIM Card with the right carrier: AT&T.
I just opened the back of my Motorola 376g and it has an AT&T SIM card in it. I checked online and they do sell it for AT&T. So it does work with AT&T.
As for advanced functions, I thought you are basically going to use his phone for emergencies and at WDW? Are you going to be using the Web access to download ringtones? Will you be doing a lot of text messaging to send pictures you took on the phone to email? The phone should still work for that anyway.
Just do what I said in my last post and get a cheap Tracfone from
Walmart and swap out the SIM card.
After you've come back, you can call Tracfone or go online and get a new SIM card to get the Walmart phone working, so you can get the minutes off that. They will send a new SIM card, (as a pp mentioned in 3 days by Fed-Ex.)
IF for some reason you still can't get the phone working, you have 30 days to return the phone for a refund. Deal with it when you come back.