I'm not sure on the node spacing but she is very branchy(kind of like a christmas tree) I don't have one of it now but I wanna get one up when its half way through flower to get some guesses.
May be,depends on the state and location. Two 400s would bump my electricity up roughly 30 a month on a 18/6 maybe more. Larger cities tend to have highter prices.
When peppers get under watered they become spicey, I had spicey bell peppers and was thinkin wtf then it rained hard for two days and those picked when it had stopped were normal bells.
You could get dos 250s and you already got some cfls. Correct me if I'm wrong but the 250 has 3x3, with cfls providing side light. I had a 150 in a 2x5x8 closet, door closed and the fan came unplugged it got up to 77 at the base of the flower pot.