As for the prop coming loose, if you don't have the "safety nut" on, put it on. This is the second nut that "jams" into the primary nut. When you use a spinner, the spinner adapter acts as the "safety nut".

I strongly suggest using an electric starter.

Make sure you are running the engine RICH during breakin.

After the engine is broken in, if the engine is not "putting out smoke", it is too lean. You need to have the engine "smoking".