I will try to answer to my best knowledge!1. Stick with fireline over mono. Dives deeper than mono (thinner, cuts through water better).I’d say tie directly to crank bait....but if you want, a 10-12lb mono/floro leader would be fine.2. I’d say no leader in that instance.3. You want a little backing, only like 10-20 yards is good(mono). Use the whole spool of leadcore, should fit perfect on the larger linecounters like that.I like to use a braid leader actually for leadcore. 10ft is plenty.Help at all??