ABS light is usually a sensor that went bad. (Happened to me twice) Easy to replace but you need a code reader to check which sensor went bad. You're basically just driving around w/o ABS.
The flashing air bag light is most likely a loose connection at one of the sensors, but you may want to have a pro check it in case you set it off (expensive to replace the air bag)
Expensive to replace the seat covers after your air bag goes off unexpectadly too... I know. My wifes Subi detonated the airbags when we bumped a curb VERY lightly (they had a recall, and we got it fixed for $0) I nearly wet myself when the thing went off, and, luckily, my arm wasn't across it.
Do you have big tires in the back? My ABS light comes on at the track when I put my 275/60 Drag Radials on. As soon as I change back to my regular radials it goes out. Go figure.
When I first got my mustang, it was flashing. It ended up being a dirty connector at the air bag diagnostic module. I cleaned it up, and it hasn't flashed since.