I can't help with a few of your problems, and recently someone posted a
great link to a how-to for the typical arm rest problems:
http://www.weidefamily.net/vanagon/
in the "interior bits" section you can click next until you see the arm rest
info..
 Regarding the sliding door, I might just have an easy fix for you.
 My buddies '85 sliding door would close and then first bump you hit become
ajar. It would never completely open, and never stay completely shut. I
fiddled around with the door,, lubing all of the linkages and latches etc.
and while it became even more smooth it still popped open. The solution that
I applied, that has worked for over a year now was to take a dremel tool and
reshape the moving part of the rear latch. It had become too rounded if I
recall correctly and the stationary pole that the latch hooks onto wouldn't
sit all the way down into the catch. hmm,, well this isn't really easy to
explain, but if you can't seem to figure anything else out,, go back their
and with the door slightly open look at the crab claw looking piece (that
turns and grabs the rear pole when you close the door) and if it looks worn
then instead of replacing it you can try to grind it out a bit so that it
holds better..
 whew,, what a poor description,, I don't feel like taking a picture,,
sorry..
 Later,
Jonathan Poole