if your not running dipseys I would run mono for flatlining, gives you some strech so your not ripping some mouths, you can run braid if you have some good reels with good drag on them.

when your trolling your going to be switching out lures a lot so it makes no sense to tie direct. I use norman speed snaps. If you use clear mono theres no point to use flouro leader just more knots to worry about breaking.

seaguar sells leader material and is supposed to be better than just using regular flouro line, I would go with 15 pound

I have used vanish on my bass rod and never liked it