No problem. I wouldn't say a ring is necessary for starting 3D (I've been doing well enough without one for months), but it is vital when you decided to begin piro-flips. That's the first big trick I can think of where you'll risk pushing into the corners.

Again, I would highly recommend the videos for any setup questions. If you're like me, they should really help you not only know what to do but also understand why to do it. As far as I know, there's nothing available in print (rather, on the Web) that is near as valuable as those videos Bob White has put together. For my two cents, I would say they're necessary watching for anyone in heli's that has never seen them.

Good luck!
- Chaz