alt Hacker NewsTurns out you are correct on both points!
My bad, NEMA 14-50R is a 4-wire receptacle with a neutral.
I learned something new today, 200% neutrals are not required by the NEC but can help with non-linear loads, and certain transformers that mitigate harmonics need 200% neutrals.
I'm thinking you'd have a hard time fitting it in a smaller residential unit purely because of the load calculations. You'd probably have to add 3000W worth of AC units or heat pumps. Considering it's 4+ space heaters worth of output, I think you could fit it on a 200A service. 150A if you're bold and use optional calcs (these assuming you have electric cooking). To your point, basically the same as if you have an EV but with some cooling in there.