I made a page the covers many of your questions.. regarding the chain driven setups, read up on " Cyclone " .. it uses a freewheeling crank, so yes, it replaces your pedals and allows the chain to spin without the pedals moving.. also used on tandem bikes..
http://ypedal.com/rant/rant.htm
what is the distance ( kms ) per trip to get from home to university ?