I almost always put a bit of worm on my wedding ring when trolling, it works great. I also like to troll flies with my 5-weight fly rod (boy, I'm gonna catch hell for that!) and then kill the motor and have some fun when I hook up. As far as depth, all of the posts above have great ideas. I use split shot on my line or a 3-way swivel with a short drop line to enough weight to get me down. Also, try trolling in a meandering pattern instead of a straight line. When you do this, your trailing line and tackle will slow down when you turn and sink deeper, and speed up when you straighten out and come up shallower. That way you cover more water depth looking for fish.

Good luck and have fun!