Size 6 is just a suggestion for a range of fish sizes you’re likely to catch on Lake St. Clair. Small enough for perch and large enough that a big bass or walleye won’t straighten it out. If you’re targeting panfish, then you would want smaller. For muskie you would want larger. As for sinkers, it depends on how you are fishing. If you are casting using a bobber with live bait on a hook, you need some weight between the hook and bobber to be able to cast farther. Sinker or no sinker (floater) all depends on what depth the fish are at.