RE: Dream 110 Electric Conversion
Check out sky lipo from hobbypartz.com. my favorite batteries are rhino from hobbyking.com.
I don't know if you could get away with 4000mah or not, but it would save weight. 20C is all you need for pattern flying.
With the new V2 hacker and good cooling you can run an 18x12. I have an 18x10 on my 14L, 300kv, and the motor is not even breaking a sweat, so I just ordered an 18x12.