This is all personal preference but i prefer straight flouro. Not a big fan of braids lack of slack line sensitivity, the density of flouro provides better slack line bite detection.
Fishing heavy cover i generally dont go below 17lb, mostly fish 20lb.
Anytime i do fish braid, except frogging, I use a leader. Its debatable whether seeing braid makes the fish bite shy but for slower presentations i am not taking the chance.