Well, I can tell you for sure that the game will never get new players with the current room system.
People use rules that new players don't understand and they also get kicked just for being bad.
That's not a bad argument, but I think there are better alternatives. To begin with, there needs to be a safe space for beginners, and when I say beginners I also include some people who have somehow made it to Lv. 60. Right now, people have to leave the beginner channel completely unprepared and have to deal with a community of frustrated tryhards. Whether you want to be on the beginner channel or not should be a choice, and you shouldn't have to create several accounts for the purpose of staying in beginner. And maybe in that environment some functionalities like kick voting or room titles could be disabled.
Then, concerning the rules, I think part of the duty of explaining those rules falls onto the interface. First off, the reason why people have to write "cpdb no F" or "noRgMK2HMGIBMG" or whatever is that there's not enough room in the title to make it more articulate. Second off, some modes (such as S5 or CPDB) have enough of a following that we're well beyond the question of whether they should be recognised and should get proper weapon restrictions like SO. That should be pretty unambiguous.
And finally, when it comes to sitting, there are many ways that could be implemented. Like, having a button in the interface when you press escape dedicated for sitting, that keeps track of how many sits there are and shows who is sitting when you press tab, with some kind of info bubble that pops up to explain what sitting is when you hover over the button. There's probably a better way to do this, and I just said the first thing that popped to my mind.