You can do ABS with 60°C chamber comfortably. I haven’t had a success print with PA yet so I cannot comment on that.
I don’t see a point for dual aux fan mod. I hardly use aux fan even when printing PLA for that matter.
That heater has main ac heater. So yes it connects parallel to Live and Neutral of the printer. For comparison, P1S can pull 4.2A @240V AC from main when it’s heating the bed, which is about 1000W, so 150W is not much but it certainly helps to compensate the heat loss that disperses to the environment.
I know a guy did this mod before and it doesn’t improve much since he could print ABS without turning it on. I, too, print ABS without need of chamber heater, but I have my P1S sit inside an insulated chamber.
With proper insulation, I think you don’t have to heat soak the chamber before print. At a first few layers, the temp is pretty much close to bed temp, and when it at certain height the active heater would already heat up to 60°C. Again, I don’t have experience with PA so I cannot comment about it.
A lot of bad things happen before the plastic enclosure of P1S melts, say: heat creep, steppers overloaded, printer on fire…
Actually, plastic enclosure of P1S does help to slow down the heat dissipation to the environment, hence it helps to contain chamber temperature better than X1C. So that you probably can print ABS without need of chamber heater