When using 20lb braid what line and length do you use? Also what baits do you use a leader with?

I'm guessing on a spinning reel?

I use 20lb braid to 30ft of 8lb Pline CXX for finesse presentations like neko, wacky, drop shot, light shaky head, ned rig, 1/4oz beetlespins

I'll use 20lb braid to 30ft of 8lb Pline CX or Yozuri Hybrid (more neutrally buoyant than CXX) for jerkbaits and crappie/pan fishing.

yes, spinning reel used for drop, wacky and light finesse presentations. But also what about worm, texas rig or?

I usually use 8 or 12 lb invisx.
15 ft is plenty of leader for me.

I use leader for drop shot.. usually about 10-15'. Invisix 10-12lb. I also have braid on my deep crank rig, but only about a 3 leader on that one, 12lb invisix there too. About 3' on shakey head/wacky rig setup.. 12lb there. I fish Joe Pool mostly and while I know there are big fish in that lake, 6.5lb is the biggest I have run across. I think the rule of thumb is to use the lightest leader you can depending on the clarity of the water. I think that JP is dingy enough to stay at 10lb and above.

BD

Usually 6 ft length. Fluorocarbon leaders are preferred in clearer water. Thickness varies from 8-17 lbs depending on application.

I use between 6’-10’ of 12 pound fluoro leader on the two rods I keep braid on. One is a spinning outfit for Ned rig, the other is an 8’ medium crankbait rod I use for inshore fishing and freshwater cranking.