#2 If I remember correctly the jib halyard is just a small line to raise the jib. You take half of it off when you tension the jib. If you have a wire, this maybe part of the problem.

#1 Swivel, I have done this once but it was a long time ago.

My memory is that the stock TheMightyHobie18 Swivel is a big shiney metal thing that is almost sealed.

I cleaned it in hot spoapy water. Soak it, operate it, hold it up to let it drain and then repeat until the black stuff stops coming out. (change the water frequently and try to get dishwashing detergent in the swivel)

Then I let it dry and flushed it with WD-40. Let dry it and soaked it in krytox. Let it dry and it worked for a few months.

I woud start looking on eBay for a cheap replacement.