The lack of adherence to many rules can be annoying. In the case of stop signs, I think there is a strong case to be made for treating stop signs as yields for cyclists.
http://vimeo.com/boomhower/idahostop
As for riding on sidewalks, I think in most cases, it's just a matter of survival until there is proper on-street infrastructure in this city. I've been trying to avoid it if at all possible on my recent foray into bike commuting to work but in some instances I've simply had to.
That said, motorists don't often know what to do when a cyclist is trying to strictly adhere to rules of the road - they often treat the cyclist as pedestrian, when they are not.
Once better infrastructure is in place, I think we'll all benefit by seeing better compliance, better safety for motorists, pedestrians and cyclists - and ultimately more cyclists.