you can definately drive w/one hanger, but if it shakes too much, the exhaust might slip off from that 1 hanger and be hangin down(its still held by bolts) which is a bad thing, but its no big deal, just take it to a shop and have them weld one for you, or you can even go to autozone and get ur own universal hanger for like 5 bucks
the brake sensor is probably lose btw