And does being endorsed for high altitude/high performance in the military cross over to the civilian world? (I.e., if you're qualified to solo a T-34C, can you go to an FBO and rent something with >200HP and take it higher than 20,000?)
With just a T-34 solo, you really can't do anything on civvie street. You need to get winged and get your mil comp commercial certificate first, for it to be legal. Then, you would need to be checked out in whatever aircraft through the FBO first, but yes, you could rent it. If you live near Willow Grove, you can even rent a T-34. As an unofficial perk, I've rented complex A/C from some pretty draconian FBO's that have 10 or 15 hour in model mins to take their complex rentals solo. With the mil comp, I just needed a quick 45 minute checkout.
@ tlord: The application is all online now; has been for a while. It's called IACRA. I think there's a provision for mailing a paper version somehow, but for all intents and purposes, FAA applications are solely done online. If you didn't do it online, chances are your certifying instructor/DPE did it for you online.