Welcome aboard.

I almost always wear a belt with a kilt. I don't have a waistcoat yet, but when I get it, I won't wear a belt with it because it won't show, and the vest will lay better without it.

The main thing is to coordinate. Don't wear brown shoes with a black belt, or vice versa. You don't wear a brown belt for dress. Things like that.

Look at the pictures of the gentlemen here for good examples.