Welcome RK
The light filtering through the hull is normal. You see this on many sailboats built to be trailerable. There is no wood core, on the hull, only fiberglass built up on fiberglass. The top of the boat, has a sandwich of fiberglass, wood and fiberglass again, so no light should be going through that.
It may need painting, but often times, a good cleaning, removing the oxidation, and then sealing it with wax is a better solution. Once you paint, paint follows more paint. Better to not paint, if you can do so.
The engine well, by the rudder, or by the entrance to the cabin?
I think the engine well, is one fantastic aspect of the 30's, and a few rare 32's.
15hp is plenty good sized for an engine, a 9.9 is all that is required.