Tapp, a lot of the problems you are seeing are my fault. I've fixed nearly all of them in the current version of the UCMP-dev (4).
The white textures are mostly textures that I was not sent. For the one person who sent a segment along with a materials folder (it was a single floor texture), I decided not to include it. Quite honestly, textures are more part of the detailing process than the layout process, and I did not feel the need as of yet to include them. As of right now, any missing textures in files I receive have been replaced with stock development textures, as they will be at release.
I've sent every person a VMF that should include the constraints for their segment. If you have any questions I'm almost always on Steam, and I regularly check my private messages. There is also a version of the UCMP available here:
http://forums.tf2maps.net/downloads.php?do=file&id=2450. if you need a reference for your work.
Tapp, if it must explode please make it non-lethal special effects (or a small trigger_hurt that deals 20 damage for a second or something. As a TC map, there is a good chance that your stage may get played more than once in a single game.
Radaka, if you are really serious you can be my guest. I'll hand the file over to you after I finish the gameplay entities and you can knock yourself out with pickup placement.
Gundam, that side point looks very nice. My only real visual concern is that the ramp up seems a bit long.