http://www.helidirect.com/product_in...oducts_id=1158
I can personally say excellent things about this UBEC. It small, Light and it just plain works. What more can you ask.
As far as the idlers... You probably only need one. Once you switch to brushless, you will just to lock it in 2nd gear anyway. You won't use first gear, its not necessary with the torque of the brushless system. If you want to use both first and 2nd gear get 2 idlers. But I would just ditch the shifting servo, lock into 2nd gear and repalce the 2nd gear idler.