I have had both of these problems on my '91 Carat.  My table was stuck down
when I bought the van as well.  Fix is not easy.  Remove entire rear interior
(including rear seat/bed) and flooring to remove driver's side wall to which
the table is attached.
Then you can get to the back of the fastener and unlock it.  I had heard from
other list members that a new mechanism doesn't guarantee that it will not
happen again so I just used magnets to keep the table down and pull up on it
to unlock it.  Some other members use industrial strength velcro which is
probably a better idea than the magnets (they get loose after a while).

The rear hatch problem on mine was similar to what you describe.  My problem
was that one of the three countersunk, allen bolts that hold the lock into
the rear hatch, had gotten loose and fallen out.  So I would check with
first.  It could also be the mechanism itself but I hope not as this is
harder to fix.

Hope this helps,
Ken Wilford
http://www.vanagain.com
John 3:16
Phone: (856)-765-1583
Shop:   (856)-327-0027
Fax:     (856)-327-2242