I haven't been following this thread, but want to offer an opinion
anyway.  If you are going to get a cheap to middling price paint job,
you can get the best job by doing a lot of sanding before hand.
Perfection is very hard to come by but it's more or less true that the
more you sand the better the finish.  I start with 180 grit dry sanding
and go over the whole car once, then go over it again with 220 dry
sanding.  You can use spot putty in between coats to get little nicks
and whatnot you may have missed before.
Then start your wet sanding...twice over with 200 then twice with 400.
I think going to 600 is a waste of time for most purposes.
  To wet sand use a rubber sanding block and a bucket of water as well
as a hose.  Change paper whenever the paper seems to lose it's "bite."
Typically I've spent 30 hours or so sanding.
  If you want to pay someone to do it for you that would be nice.

John Jensen, Mudbug Pottery
mudbug@toadhouse.com , http://www.toadhouse.com