This should go without saying, but could you please not include textures with racial stereotypes and potentially offensive words?
Some minor things:
Lots of details could stand to have clip brushes (ex: strips of wood on the walls, metal on the windows.
Are you compiling with -extra in the rad stage? Some of the lighting looks a bit blocky, but that may be all we can get out of the lightmap resolution.
As for gameplay, most of the paths you mention just get you to the floor below the flag -- that's not usually a problem. It's the flag floor itself. People are either going to come up the stairs or the couch jump pad. Even the (very subtle) roof path drops in right where the stairs are. That plus the fact that you can crouch behind and shoot through the chairs makes it REALLY easy to defend.
Oh, and you were asking about sounds being too quiet before -- it's actually possible to set attenuation values between 0 and 1, ex: 0.5 would make the sound range twice as far (as it sounds like it's only half as far away). This only works for non-looped sounds, though.
