Your choice of servos sounds perfect to me, especially for 3D maneuvers. In my airplanes, I use a 2100 mah 6V NiMH pack for my receiver/servos, (Futaba PCM receiver, Hitec servos). For the ignition, I use a 2100 mah 4.8V NiMH pack. The way you describe your battery set-up, it sounds like you're hooking up two batteries to one receiver, which would require a voltage regulator. If you use a higher mah battery, you can avoid needing two batteries and a regulator.

For those of you that want to buy battery packs for less, try Ebay. There's a company on there called Battery Island, or something like that. I bought three 6V packs for $17 + shipping. They have worked flawlessly for me for quite some time now.