1997 Chevrolet Lumina Check Engine Light Code P0705

Hello you are my go to guy to ask questions before I get work done to make sure I am not being duked. :-) I have a few questions before I take my 1997 Chevy Lumina into the shop. My "Check Engine Light" came on 2 days ago. I did discover my gas cap was very loose and thought this is what triggered the C.E.L to come on. After riding around and it still remained on I decided to take it to Autozone to have them check it for a code. Here is the information

Code: P0705
Definition: Transaxle range switch fault
Explanation: Vehicle speed registered and EMC detected an incorrect input from the transaxle range sensor
Probable Cause: Failed transmission range sensor
Open or short circuit condition

My Questions:
Is the transaxle range sensor the same as the Neutral Safety Switch?
I received a quote of $150 is this accurate?
Is the Open or Short circuit condition a separate problem or a result of the transaxle range sensor being bad?

I had my transmission rebuilt 1 year ago should these parts be failing now?