1) On some YS 4-strokes, fuel does drip into the carb after the engine is turned off. Most YS 4-strokes are mounted inverted, and if this is the case, then you get some fuel dripping out of the carb. This is not really a concern. You can reduce the chance of this happening by unplugging the pressure line to relieve tank pressure after shut down.

2) The piston rings started to seat and your starter battery was getting low.

3) That is not normal. I have seen that happening once, but not on a YS. I usually use spinners with aluminum backplate.