^^ you guys are too fast for me.
Nice to see somebody else is challenging Radiant, too. Welcome back.
You are on a good way with your map. As people love pics in threads i made one of your your map. Hopefully this is ok for you.
Two things you might want to take a close look at :
a) As far as I know having walkable terrain below zero may cause errors in pathfinding. You can change this easily this way :
by setting the grid to 64 (<7>) - hit <shift>+<h> - selecting the whole map - shifting it up one level. After this using -> 'Tools' -> 'one level up' will change the levelflags accordingly.
b) All starting positions should fit into grid 32 (<6>). If they do not, the game will refuse to place the actors. Also, to make it playable in scirmish-mode you will have to use 'info_human_start' instead of info_player_start. Those are used for multiplayer.
If you post an updated map, I will further investigate and come up with some suggestions how you can improve it.