Hi o_lampe, thank you for your reply.
I didn’t plan on using capacitors in the high current circuits for the motors, maybe I should? Anyway, without capacitors, the precharge resistors are probably redundant, thanks for pointing that out. I’ve got a small delay in my code to make sure that the contactors are closed before the motors are started, so hopefully, that will take care of sparking.
The safety-switch is actually the “seatswitch”. I’ve also programmed for a “soft throttle response”, and the mower is going to be quite heavy, so I don’t foresee any wheelies, although the redneck in me kind of wished I could pull a wheely on a lawnmower 
Also my code makes sure that the mower can’t be activated if the throttle is pressed at startup.
All input switches are taken care of by the “Android user-interface”. I’ve attached a picture below.
Where I am in most doubt is regarding the mosfets and mosfetdriver I’ve chosen, my mosfet-circuit, sizing of flyback diode (I’m now thinking of using these http://www.diodes.com/datasheets/ds31413.pdf, as I already have two of them for another project) and noise suppression capacitors. Does anybody have any input/suggestions on this? I would like to avoid buying commercial motor controllers, if at all possible.
