If it was me, I'd clean the carb and not mess with jets or shims. Unless you are in a special situation adjusting the idle will probably do after a cleaning. Inspect those tires to make sure they have not aged in the 10=12 year, and probably you should replace them if you can conveniently afford to do so for safety sake. They could be make the highway noise of knobby tires or have a flat or wear spot that you are hearing.
Everyone has a different viewpoint on sprockets, but again ride it awhile and decide for yourself. Maybe Mr. Yamaha knew best about the gearing. JMHO. Tom