The plugin has nothing to do with the number of real spawn points per map. It simply creates fake points and teleports you to one at random on spawn. The plugin is not your problem therefore.
- Check gamemodes.txt and that "maxplayers" is set to 30 for each map.
- Delete or modify any *.kv files in the maps folder that may be overriding map settings.
- Finally, I'm told, some stock maps support 30 players while others only support 10. Many have had success using the Spawn Tools 7 plugin to add spawn points, available at http://forums.alliedmods.net/showthread.php?t=115496
As for FFA mode, I'm not sure exactly how that would work, but I will look into it. I think CSSDM has a FFA mode.