Like I said, just personal preference, but you will find your own way as you become more adept at this stuff. As far as depths of cannonballs and colors of lures, etc., you will do a lot of experimenting, trust me. If you are fishing for lake trout later in the year, always troll slow with the baits towards the bottom. Slow is about 1.0 to 1.5 mph. Another thing, before trying a bait at a certain speed, just put it on the rod and hold it in the water a few seconds just to see if is working properly and not spinning out.
Currents are really awsome things and play havoc with lures.
Just test them and look for the nice wobble, never a spin. They particularly like orange colors mixed in. They are killers on brown trout and coho. Casting for Coho, Browns and Steelhead at the Power Plants. If while trolling in the springtime, you happen to find a pod of coho in the shallows, always have a casting rod with you and some little spinners such as rooster tails or even just some cut spawn, and if in waters that are shallow enough and lake is not too wavy, anchor and cast for them.