this thread is just to long for my tired eyes to read thru ATM, but let me suggest a few pointers, that may or may not have been covered already, use this advice, or ignore it, doesn't matter, but do not come up later and cry, because you didn't listen 
1) planning out a maps layout is all fine and dandy, but in practicality, you are only wasting your time, usually something or someone will skew it and it will go to s**t rapidly, just chose the order of who will add what, and when and you will be ok, thats about all the layout you will need in advance.
2) chose a theme, stick to the theme, do not vary from it.
3) chose a texture set, and stick to it, remember not everyone has broadband, and you will seriously handicap anyone on 56k if you add 25 megs of custom textures and sky's.
4) pick a time limit on each persons addition.. a week to no more thaN TWO is sufficient.
5) additions can be made in advance, for those wanting to add theres rapidly upon receiving of the rmf..
6) KEEP the format in RMF, because after you go thru the trouble of visgrouping, and some asswipe removes it all by sending you the .map file, you WILL BE PISSED!
7) r_speeds will not be an issue, just because it is a multi-member creation, if you adhere to visblocking and so forth, the r_speeds will be fine, in spite of its size, remember not to create oversized func_walls, because YOU WILL effect everyone elses r_speeds.
8) pick a leader, doesn't matter who, but let them decide the decisions that will arise... group decisions only work so far, then they become moot.
9)finally, try to incorporate your addition without the need for miles of interconnection, and boring hallways.. do not forget, you have an UP and a DOWN direction as well as linear layouts..
i wish you all good luck, and want you to realize, this project will be the best fun you have ever had, but, its not finished till its completed, so if you are thinking its already a done deal.... you will be disappointed..
[addsig]