I'm trying to add 50 beta testers to my app through ad hoc. In the portal, it gives you an option to upload a file for UDIDS. What format should it be? Also, it mentioned that you are only limited to 100 devices per year and they cannot be changed. Does this mean once I added my beta testers, they cannot be changed forever, even for other apps?
I'd start with trying a simple newline-separated file of UDIDs. Make a plain text file in TextEdit or Notepad, then format it something like:
UDID1 UDID2 ...
As for the 100-UDID limit, you can delete those whenever you like, but you can only add 100 devices per year. So if you add 50 now, and 50 tomorrow, that's it for the year. You can delete all of them a week from now, and you'll be stuck with 0 UDIDs until the new year, since you can't add more than the 100 you already used. Moral of the story: add UDIDs carefully.
I just verified how it works to bulk upload devices. You should use a tab delimited text file that looks like:
device_id_hex_40_chars description_text
... ...
Save this as a text file and upload to iPhone Developer Program->Devices->Upload Devices.
It should also be possible to upload a file in XML-format, but haven't found documentation how that's supposed to be structured. I guess it's easier if you're in the Enterprise program and can manage all devices in the iPhone Configuration Utility.