[bestgenman]

Does the 20kw generator have water circulated in it from the aqua-hot system to warm up in cold weather?

Not unless someone has altered the piping.  Newell typically did not preheat the generators to my knowledge..
You could tie the generator into the engine preheat loop without too much difficulty but I believe I would use a braised plate heat exchanger to prevent coolant loss to the generator set.