Hello !
If it's for a solar car, is there any pedal assistance? If so, I would choose the Mini Motor for the freewheel ability.
If no pedalling, and want to use like a light car, then Magic Pie with internal controller on a lightweight 20" wheel would be a good choice. But if the car weighs more than 100Kg + the driver you will need 2 of them if there is any hills
It will not be 1000W, more so around 800W Max, Yes - you can connect the pedal throttle to any of the brushless controllers.