First, there is a bug with 4+ players when people die, such as defibing the wrong person, etc, try installing this,
https://forums.alliedmods.net/showthread.php?t=118723
For your second point, any time you want to change a plugin's cvar, you must use the sm_cvar command, for example, instead of just writing into the console
l4d_csm_admins_only "0"
you need to write
sm_cvar l4d_csm_admins_only "0"
typing the survivor names or the first letter into the chat also works, and these commands are not admin restricted, such as !zoey or !z for Zoey, !n or !nick for Nick, etc.