Titleist works in mysterious ways. Having a complete profile, including ball preference, and participating in the discussions will increase the odds of being chosen. There is some randomness, as not all Pro-V users can be included in pre-marketing testing. The release cycle is 2 years, and testing for this cycle is likely at the end with the 915 Pro-V's coming out at the PGA Show in late January. Later in 2015 they should be testing the non-urethane balls with (lucky) end users.

This is true. If you want to be a tester you need to actually provide feedback. I always provide feedback on what they send to me. I try to be as honest as possible too because eventually I'll end up playing the final product!