Re: Bass Taper Line from Bass Pro
General rule of leaders - I'm not sure if there is one. Some say one to one and a half size of your rod length. Some say it depends on the fish that you are throwing flies at and the sizes of the flies that you intend on fishing for. I lean towards the latter.
As for leader material, choose the one best for conditions. If I plan on fishing areas with a lot of snags (downed trees, rocks, coral), I would use fluorocarbon. It is more abrasion resistant than monofilament. If snags are not an issue, or I am fishing topwater, or the fish are not leader shy, I fish monofilament. With some of the toothy fish that you wish to encounter, you may want some wire tippet.