Use the NADA Price Guide to find that information. You need to find the model # and know the different options it has to get precise pricing information. It is very similar to the price of a car.
Need to know the model of the trailer.
That's going to depend on the exact model, interior, other options, and condition.
Is it a diesel? If so that is why. If not then perhaps it was setup to pull travel trailer of some kind.
The cast of Trailer - 1997 includes: Pablo Ballester Marisa Lull
Yes, it is able to tow a trailer.
with wires
Fuse # 7 - 20 amp maxi-fuse - for trailer park lamp and trailer stop lamp
The pre-1997 Western Stars, before the brand was bought out by Daimler A.G. other than that, they pretty much all depreciate in a similar manner.
Yes, if what you are talking about is a pop up trailer, around 2,000 lbs. The air springs can hold this weight if the car is equipped with. Just turn off the over drive and keep the speed around 100 kms or 60 mph. With the over drive off, the transmission will not heat up.
Some parts will be compatible, yes. There shouldn't be much difference if they're both the same model.
The trailer harness plug should be located behind the rear license plate holder. Some 1997 Chevrolet Tahoe's were not equipped with the trailer harness plug.