1997 ford mustang convertible help/advice?

The brake light problem is probably a bad brake light switch, look at your brake pedal and then follow the metal piece on top of it up until you see where the switch contacts it. The door panels are held on with plastic push pins, you can get them at most parts stores. With the panels secure the door handles should stay in place also. Epoxy or glue would pretty much be useless. If you need any used parts I recommend www.car-part.com .