If it's hanging down, it's not in good shape at all- the headliner is made up of a layer of fabric (what you see hanging down) attached to a layer of foam, which is glued to a fibreglass board.
What's hanging down is the thin layer of fabric, which has detached from the foam and glue. There's no way to reuse the old one, without problems at least.
Your 2 options are:
1Buy a headliner kit (40-60$) consisting of a length of new material, and glue it on the cleaned up old board.
2Buy a new headliner altogether (300$ from BMA).
I tried option 1 and screwed it up- one of the problems was that the high temperature of where I was working made the spray glue dry faster than normal, but the main reason is that... I screwed up. There are many "ridges and slopes" in the board that you have to work the fabric into, without really stretching it. The other problem is matching the color.
Getting the thing out is relatively simple, luckily. It just takes time to remove all the screwed on bits, and adjust (or remove) the seats to fanagle the thing out. Be careful not to bend it too much, as cracks can (and in my case DID) develop. Also, be careful not to scratch or press too hard on the board when removing the old foam, because some sports are soft and have foam in certain areas, that can be scratched off, leaving deep gashes which show up when new fabric is put on.
So now I'm driving around without a headliner, waiting for my new one to arrive. I'm also doing the rear shelf, which has the same problem. The rear shelf is hard to find, and that's what I'm waiting on basically.