Re: second seat, foot pegs/highway bars, lighting kit?
if you put highway bars/footpegs on and keep the cranks and pedals, the cranks will turn slowly and randomly on their own, which could be pretty sketchy leaning into a corner. if the pedal digs into the ground while you're turning, they make great catapults.
without the cranks and pedals, you have to push start your bike and scooter it away from stops, unless you have a pull start and a shift kit.
just some things to think about.