The right side tail light on my Supra had come loose at the top right corner.  A problem many of you are familiar with.  Fortunately I had a parts car to steal this from.

I was able to do this without removing all the skin inside of the hatch.  I took off the very back panel and loosened the side one.  With this done I was able to slide my hand behind the panels and loosen the light.  There are 6 nuts holding the light in.  Since my car had been wrecked on this corner, I used RTV to make sure the gasket stayed sealed to the light and the light to the body of the car.
 

1- I had to be very careful when pulling the plastic skin out and getting my arm underneath it.  Pry too far and it can crack. 
2- The outermost two nuts are inside the fender about 4 inches and at an extreme angle. 

None.

I now have a light that isn't separated.  I'd say that's a good payoff, especially in light of the fact that it was free for me.  I still have some water coming back here though.  It has to be the wiper or the window, and I've had the window replaced.