With regards to your shifter - the shifter has two interlocks, one is mechanical, and the other is electrical. The mechanical goes to your ignition switch - I think it stops you starting the car if you're not in park or neutral. The other is a solenoid in the shifter assembly and sometimes the retracting spring breaks (I think it keeps you from shifting into park or reverse if you foot is not on the brake.). Have you tried the manual override on the shifter - you put a blunt rod/pencil in the hole at the back top of the shifter to manually bypass the interlocks.
-Jerry