steamgroup exclusive i believe allows friends of people within your steam group to join. I can't say for sure I've never really fiddled with it.
A testing version is already in the works and everything looks sound, just need to pull a testing group together to see if we can get tank spawning. If it works then viola this could be the final iteration. I'll also be quickly looking into making medpacks at the spawn point equal to survivor_limit (with an option to enable/disable) as some people have been asking for that.
As for being unable to join survivors, it's a stupid coding oversight on my part so I'm working fast to get the next version out.