The number of testers selected for a particular beta test varies, and the qualifications are listed on the application page. Our beta test program is not like those at places like RealArcade, Big Fish Games, and Pogo where they are evaluating finished games. We are actually testing and debugging the games. We are looking for people who have the time and willingness to really work at testing game function and playability, and who can communicate well with the development team, because that's critical in the beta test process. Some of our best beta testers have little technical ability, but they're good communicators who are observant and dedicated.
To be honest, we have far more people wanting to be testers than we can possibly choose, but we try to bring new testers into the program with each new beta test.