Basketball was still a pretty new sport at the turn of the century (created in 1891). I've yet to see a depiction of Frank playing basketball, but of almost 900 issues, I've also only seen a limited sampling of covers, so it could be that I just haven't come across one.
No idea what the "M" stands for on this one. A local league, is my guess, since, again. Frank was probably in New York when this issue takes place.
I have a cycling outfit and another set of street clothes, but neither are painted. I may not get to them until next weekend.