Re: Sounds funny
It's probably knocking/pinging/clacking/tapping at all RPM ranges, but the Db level is low enough at idle that you can actually hear it. Without hearing the sound, it's REALLY tough to tell. It could be bad gas, it could simply need a valve adjustment. I'd put my money on the valves needing adjustment.
the squeel is most likely a belt.
Belts can stretch and valve's can tighten a bit during break in and typically should be checked at the first scheduled maintenance interval. This is one of the reasons the first scheduled maintenance is traditionally so short. I would expect 35 hours is past the first scheduled maintenance, isn't it?
Do the RPM's eventually rise and the roughness go away if you don't put the boat into gear and let it warm up on it's own?