With regards to a knee support, don't bother, your knee will be better without it in the long run.
When I did my ACL, I thought about having a support on it, but your knee has to learn how to be normal again, and by helping it with that, your not using your full motion and it will never properly heal itself.
You need to do some physio to tighten the muscles around your knee, but that's all you need. If your muscles are shit around your knee, then a support is probably necessary. You really need to get your quad and hamstring nice and strong.
Good luck, its a nasty little injury.