Ride in the street
If the road is narrow; don't squeeze to the right, this will only put you in danger of car doors swinging open into you; as well as encourage cars to hit you with the passenger mirror as they pass you.
instead when the road is too narrow and has no bike lane, ride in the middle of the lane like a car or motorcycle would.
Sidewalk riding is usually illegal, and it is dangerous for you; cars pulling into driveways don't usually check that a bike(or pedestrian for that matter) is in the sidewalk they are crossing.

Obey stop signs
here's a good tutorial on how to stop/start the bike http://sheldonbrown.com/starting.html Should help smooth things out.
also possible that your bike is too big for you....

I just step over the bike from the middle
maybe your bike is too big for you.... or if there is some physical limitation in how high you can raise your leg; a step-through frame may be needed