A motor will only
pull as much current as it needs to get the job done, batteries cant
push current to the motor.
Hooking up 6s lipo will just increase the voltage to the esc and motor, the availablke current will stay the same- the power potential will increase though (power in watts = volts x amps).
The old 18.97 esc was purpose made for the BM motor, so it should still run fine, but then again, its a schulze afterall (Serum has a photo album full of toasted escs from that company....).
Timing on the shculze I think is done via those little dip switches- no clue about how to do that, but there should be a guide somewhere on their website, or seek out the Candyman- he still has an 18.97k with his BM motor in his truck 'MaxxBling'.