If your team is BLUFOR, create a trigger activated by OPFOR not present, covering the whole map and select any end (like end1) in the type list.
How to keep your team spawning, well you're making an MP mission. So you need a description.ext with:
respawn="3";
respawndelay=20;
In the editor, create a marker named "respawn_west" (use F6). That should do the trick.