I use Gamakatsu and Owner Stinger 36's for my cranks. You can get Gamakatsu in packs of 25.
Split rings I usually only replace if they're bent or rusting. I generally use Mustad KVD stainless one's, or if it's a cheaper lure, I use the cheaper Eagle Claw one's.
As for the braid thing, my Dad will reverse his line once it starts fraying and loses its color. It works for him. I personally just replace it once it gets low or starts looking shotty.