I agree with what most others have said.
I don't believe I have ever lubricated the upper swivel. It sounds like you've either got too much rig tension or you're trying to unfurl with the mainsheet tight. In general I run a loose to very loose rig on my 18. You definitly don't want to be so tight that you restrict mast rotation. When unfurling, the point of sail doesn't really matter, just be sure the mainsheet is slack. When furling in moderate to high wind, it's easiest (but not necessary) to be pointing downwind so the forestay is slack and the jib is blocked by the main.

As for the halyard jumping off, I've never had that problem. I would do what others have suggested and squeeze the housing closed. Otherwise perhaps a slightly larger wire diameter would do the trick.

sm