I think brown shoes look really sharp with a charcoal gray suit. You'll want to match your belt with the shoes. Check out this recent thread over on the Style Forum: http://www.styleforum.net/showthread.php?t=166367
I can't help with the watch color, though matching does seem logical. Spend some time on Style Forum, it's an excellent community where I'm sure you'll find an answer.
Picture from the thread linked to above: