1: I never had trouble with that. :blink:
2: Thief is supposed to be a very dark game, but it sometimes overdoes it. When absolutely necessary I tend to turn up the gamma on my screen, and turn it back down when I'm done.
3:Personally I loved the way Thief handled maps
. They let you do the work yourself in a more realistic manner.
-Slight spoilers:
I did it pretty much the same way. I stood in the center of the great hall, threw a skull on the ground and faced the hordes. It was a bloodbath.
As far as I know you won't be facing such legions again.
The sword and arrows still have uses against non-human opponents.
If you put some efort in, most missions will not be too hard to navigate. Some of the other missions (those which are illogical in build) were meant to be very hard to navigate. In those missions the map is only a guideline and, in a way, you'll have to make your own as you go.