Ok so I ended up going with the 5700kv, battery questions?

Welcome to the forums. This subject has been visited many times. Do a bit of research. There is lots of information here.

Asking what kind of runtimes you can expect is kind of a loaded question. It all depends on the terrain, your driving style, the vehicle, the tires, etc.

If you want the most runtime, just get the biggest battery that you can fit into your vehicle. The 5Ah packs are a good bang for the buck and a good trade off between weight and runtime.

If you can afford it, go with lipo. It's just plain better all the way around.