There are certain sidewalks that are ok for bicycles and ones that aren't. If there are storefronts and are very narrow, then there shouldn't be bicycles, but in a residential neighborhood where there is grass on either side, it isn't a problem.
Running a red light isn't common, and is just like jay-walking. I only do it a three way intersections when pedestrians wouldn't stop either. And only if I'm riding on a big sidewalk.
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And I always ride in crosswalks, but there are no people walking. I think the reasoning is because cars don't expect a fast moving person in the crosswalk that isn't there and then suddenly is. But, I am always watching the cars.