RE: sticking shift button
Is your brake switch working right? Ford's brake switches have a history of being malcontent. From the manual...
Brake-Shift Interlock
A shift interlock mechanism is used on Mark VIII vehicles with an automatic transmission. This is to prevent shifting the transmission out of the PARK position unless the brake pedal is depressed. The system consists of a solenoid assembly attached to the key interlock assembly, a bracket retaining the solenoid, and the necessary wiring. The solenoid is energized when the ignition key switch is turned to the RUN position, locking the shifter in the PARK position. When the brake pedal is depressed and the stoplamp switch is activated, the shift lock solenoid is deactivated and the shifter can be moved out of the PARK position.
I've seen trouble with the harness connection to the brake switch as well. Next time, locate and try to wiggle the brake switch wiring harness while depressing the brake pedal and trying to shift out of park with the e-brake engaged.