I have a comment on the noise question.

Two strokes make a more annoying, higher pitched noise. Four strokes make a lower, more realistic, more agreeable noise (my opinion). However, the four stroke noise carries for a longer distance. Someone a quarter mile away from the field will probably hear the four storke louder than an equally powerful two stroke. Apparently the higher pitched sound is dissipated more rapidly as it travels through the air.

Our club was trying to secure a new field on state park land. We put on a demo flight for the homeowners organization at a nearby development. I stood at the development along with some of the homeowners. The club flew demo flights at the field site using both 2-strokes and 4-strokes. We could hardly hear the 2-strokes but the 4-strokes were very noticeable.