870 Mag ..

yes you can use divers without boards but nee to make sure that you troll in a straight line or you will end with a big ol mess of fishing line and divers! no fun..

The jet diver will pull on the rod but wont hurt anything at all... if you don't use boards it wont pull near as hard as if you do use boards.. either way is perfectly fine if you have trolling rods..

I would recommend 40 tru trip jet divers .. they are easy to use and work very well.. most guys I know run them and love them..

I would recommend if you want to run boards just starting out that you try the yellow inline boards first. just set your diver and lure out to your desired distance then clip it right on to your fishing line and then let more line out until you are satisfied with how far from the boat/ other boards it is.. once you get the divers you can in fact run harnesses and spoons off of them.. you will need some kind of leader going from the jet to the spoon or harness (length of leader is personal preference)

line counter reels are definitely a major help!! yes stubby is right .. sometimes they don't work but that can be fixed by calibrating the reel.. there is a pretty good you tube video on how to do so. line counter reels don't actually count the line that's being unspooled .. they are designed to turn the numbers with the revolution of the spool itself which is predetermined from the factory.. it all has to do with the diameter of the spool (how much line is or isn't on the spool) .. it sounds confusing but once you watch the video and do it its really not that bad and honestly worth the little bit of confusion so you know its accurate..

I would recommend stopping into Dreamcatcher Fishing Bait and Tackle on route 2 and talk to Dave sometime..he is a very good friend of mine and very knowledgeable and will be able to get you set up and explain the whole deal start to finish with what you need .. No I am not trying to get him more business or am in no way affiliated with any sales made at the store.. he is the one that got me set up trolling and he is successful at trolling and is willing to help out anyone whether you buy your gear from him or not.

I hope this helps