When I decide to set up a beta-test for an app of mine, is it that I can share up to 100 variations of that one app? Or does the 100 include any app that I develop?
The 100 represents to total number of unique devices you can deploy ad-hoc apps to. You can deploy thousands of apps via ad-hoc but only to 100 different devices.
With four full apps in the store I have only used 5 of my 100 ids. Unless you have a massive dev and qa team I doubt you will ever run out.