RE: RX battery question
A buddy of mine used to run 50 mah packs in his boats and they would last for a day of racing. Not me as I have used some 400's in my boats as the smallest. Even then I like to throw them on the charger after a couple of runs.
In the .12 boats generally there isn't a lot of room in the radio boxes plus there's a lot of weight difference so I have used some 4-cell packs from backyard flyers.