Starter sounds like the bendicts is not throwing out like it should. You could try lightly tapping it with a hammer to see if something is sticking it in. Best bet would be to just replace it. As far as the shifting issue, like you, I'm new to the jeeps and mine does the same thing but with 4th gear mainly. Sometimes it just doesn't want to shift into any gear at all. I dunno much about them so I plan on replacing it, the flywheel, and the clutch.
1989 Jeep wrangler YJ. 4.2L 258 in-line6, front dana 30 rear dana 35?? NP231 nothing fancy yet.