How safe is it to do the train trip from Muizenberg to Simonstown? Is there safe parking in Muizenberg?
Has anyone been to the Brass Bell in Kalk Bay recently. Is it worth going to and what days do they have live music?

That distance is reasonably safe during the day. I would not suggest that you use any other station before Muizenberg. Others may differ from me, however.....
Brass Bell is ok. The food is good etc. The reception could be better at most times so i am not crazy about the place. I always went there because i had to. I have no idea about the "live music" schedule so check out the website.

The train ride to Simonstown is completely safe; I made it a few times (from Newlands) last year and never had a problem. However, like africanj I would be wary/a little careful about using it after dark. There is plenty of safe parking in Muizenberg, particularly right by the beach.

I see that there is now a "tourist train" from Cape Town to Simon's Town. With optional stops at four places en-route.

See http://tinyurl.com/394k5v

There is a "hop on hop off train" trip in the planning. It is still far from being fully operational, so don't count on any miracles.