How long is a tailbone injury going to keep me out of playing football or soccer?

Depends. "tailbone" injuries can be very painful and for a very long time. Pain will probably dictate your return to your sports. Of course re-injury can occur but that is a risk you take. Work with your doctor, sports trainer and coach on when to return. You may need to see someone skilled in injuries in this area. Sometime it is necessary to remove a tail bone due to pain and to restore activity.
Depends. Usually it will keep you out of activity only as long as it is symptomatic. Most tailbone injuries are treated conservatively and do not require any surgical intervention. If you can tolerate the discomfort you are probably safe to return to play.