handbrake mainly, but sometimes with low fluid or worn pads wired into
it. Consult you manual ;)

I can fix both of your problems.  Lots of people have fixed the glove
box problem.  Here are some of their solutions:

1) http://www.matthewsvolvosite.com/glovebox_fix_850.php

He opens the glove box by drilling a hole in the door and using a coat
hanger to push the release open.  Then he fixes it.

2) http://www.volvo-forums.com/t2328-how-to-open-a-broken-glove-box.htm

He does it by prying the door slightly so he can break away the catch.  
Then he fixes it.

3) http://www.brickboard.com/AWD/index.htm?id=1032997

He cuts the catch away and replaces it.  Make sure you protect the door
with duct tape.

Now that you have opened your glove box, you can look up that warning
light.