Re: Sailboat under $5000 for Puget Sound
I don't know about #1. But your question applies to the bottom fouling.
As for #2, marine plywood should have been used. However, water has to get to it. If the surface is well sealed to prevent spilled water from getting to the plywood then dry rot is your only concern which could take years and years. You can help slow/prevent this by painting /sealing the exposed bottom side of the plywood as a vapor barrier.