The turnbuckle can go. So probably can the hooks on top of the forward decks. They just tear things up.
Your Rotation Limiter is a solid stainless steel rod that goes into the hole underneath the boom. A bolt threaded into this from the front of the mast. Then a bit of line ran from the boom around a block at the end of the rod and back to the boom to limit the rotation. I think there was a recent discussion about the over/under rotation limiters. You can see the scars on the boom where the rod hit the boom while the sail was down.

Your jib downhaul could be a 3:1. Tie the line to the halyard (looping around the block) and add a block to the saddle the line is currently tied off to.