Rules of the road-and sidewalk?

Sidewalk - usually; road - same as cars. Unless there's a sign, in most cities you are allowed to ride your bike on the sidewalk. You still have to obey all the rules of the road though (stopping at stop signs, etc.) Bicyclists on public streets have the same rights and responsibilities as automobile drivers, so basically if you think about what you would do in a car, your answer is the same (except for the whole wearing a helmet thing).

It's More Dangerous to Ride on the Sidewalk. This may sound counterintuitive, but every biking expert will tell you DON'T RIDE ON THE SIDEWALK. Ride on the street with traffic, following the same traffic rules as automobiles. The reason it is more dangerous to ride on the sidewalk is that cars can't see you and they are more likely to hit you coming out of a driveway or making a turn onto a road. In fact, I learned this the hard way when I was in college. I was riding on the sidewalk and a car pulled out from a blind driveway. I hit the car, flew over the top of my bike, and landed on my face. I ended up in the hospital, but I was OK. By some miracle my face mended without scarring. But I can now tell you from personal experience that sidewalk biking is really not a good idea...unless the road is exceptionally narrow and the sidewalk is not peppered with driveways.

In most states, bikes are considered "vehicles"... Can't drive your car on a sidewalk, so don't ride your bike there.  If you do, you'll quickly learn about people hopping in and out of cars, and building doors opening w/ people not paying attention (not expecting you there). 

When you're on the road, stay right but give yourself enough room that you feel comfortable.  Learn signs and signals so that you can "show" cars what you are planning/need to do.  One outstanding point... stop @ stop signs, and wait in line @ stoplights just like you're a car!  With a little practice and experience, you'll be all set!