If you do the swivel approach, I have just read in the past week, the ball bearing swivels are the way to go. The forum I was reading, some salt water forum, showed a bunch of graphics and links to support the claim of how they are better. Enough for me to pick up a few 50% off... Supposedly run a lot more true, for getting the twist out of the line, which at times will have your offering twisting in circles when it shouldn't be. If just using for a connection, then I guess not worth the extra cost. They are a bit larger too. Others that troll more, and have more experience with them, might have more input if worth it.
Do some searches on here and the internets in general on lead core line. If you are fishing Pymie, that seems to be what many use there. You'll need a dedicated rod or two for it. I just set mine up, so a rookie with using it. But, from the sounds of it, the most consistent way of getting your offering deep on inland lakes.