The only thing about jumping the safety switch is that it’ll start without the clutch in. Obviously, since that’s the point, but only you can decide if that’s what you want. You will REALLY want to make sure the car is out of gear when starting. No other effects as far as I can tell. Any reason why you want to do it though?
As for the manual ecu, it’s not needed. There’s a thread specifically about using the auto ecu in a manual swap: IS300 MAuto Mod - Ultimate manual swap wiring - NO CEL -...