Ayuh,.... The "Right" prop will allow the motor to run at or very near it's stated max rpms,.....
Smaller pitch gives better low end, not bigger,....
Moving this to the prop forum,....
Ayuh,....Unless yer fuse box has a separate buss bar, No,....
Grounds are separate circuits, so there oughta be a buss bar near the fuse box,...
Ditto switches, unless the switch has an indicator light in it,....
Ayuh,.... The only guy in the entire country that I know of that'll work on yamaha sterndrives is Capt Ken Nelson, somewhere down in Fla,.....
'n he may have retired by now,....