Re: 2 or 4-stroke
Its cool you ask others for advice about these machines, but in the end it all boils down to personal preferences & abilities.
Mountain bikes often incorporate a suspension for a smoother ride, but lack the visual appeal of a cruiser design. You can look cool or ride in comfort, but you can't have both, not for cheap anyways.
2-strokes offer the best cost efficient solution to motorizing a bicycle. They are very cheap, lightweight, very simple, and offer the best acceleration to weight ratio. They also look much more like their bigger, older motorcycle cousins. They also bear the shame of lowest quality & reliability. A mechanical aptitude is manditory to setup, own & operate a HT ChinaGirl.
Electric motivation is the easiest setup, quiet & environmentally friendly. Its also the slowest, with a limited range, sluggish acceleration, very heavy, and the highest cost of ownership: expensive to buy, expensive to replace batteries.
4-strokes offer a cheaper alternative, with greater reliability over most 2-strokes. However, all things being equal, 4-strokes lack the torque (hill climbing grunt and accelleration) that 2-strokes have. The increased complexity of a 4-stroke also adds to the cost & weight. 4-strokes can have a higher output & top speed when compared to a same sized 2-stroke, but not always.
So in the end it boils down to preferences & skill level. If you don't know the difference between a socket wrench and an allen wrench, take the bus. But if science & math are your thing, then by all means get a ChinaGirl, it takes a clever mind to wrap your head around the chemistry, physics & mathmatics of a 19th century designed powerplant.
And check with the campus you attend, many schools forbid motorized vehicles on their property (except wheelchairs for the disabled). You don't want some trigger happy rent-a-cop to send you and your bike home to momma in a box.
By the holy power of Love, Life & Laughter, I commend you to Go Forth & Be Awesome!