I can recommend a cargo bike with a Bosch CX motor (the new gen4 motor looks pretty good!), makes hills a non issue. The motor is torque-y enough to deal with going up them fully laden.
Can’t speak for bafang and other options as I’ve never used them :)
That could easily be done. But this bike is not heavy so motors are not necessary.
I would like discuss motors on bikes actually. I think it is a bit of a slippery slope.