coop maps

I've seen some coop servers out there, but the maps are really sucky, yeah good npcs and stuff but in the end it looks like crap, they dont put cubemaps, even one, the shiny parts of everything look grey and ugly, and most water places have the classic pink/black "chess" texture.

What I want to know is how to make a sistem like what they had, to force players to spawn in one team, and to make npcs spawn once in a while but not crash the server.

best way to learn it is to VMEX a few coop maps (js coop maps are good for that) and look how they did it.
because there are not much tutorials on making coop maps,and alot off forums did not have the answers for it. i did it also this way.
try that first and when you have questions about it i am happy to give you advise/answers.

good luck