Some questions...

1. Are infected allowed to KOS non existing players and themselves?
Some people got buttmad when I did so, but the in-game rule states:
"[HELP] You are allowed to lie as much as you want as infected, but accusing another player (KOS) is strictly prohibited."

2. Can infected use the roof of the church on Mainstreet as a sniper vantage point? Because that roof can only be accessible only to infected (due to survivor-blockers). Also bare in mind that; that roof is on one side of the map, so its not completely OP. To gain access to the roof, you simply climb the pipe located at one side of the church.

Buttmads almost vote banned me for using this spot, so with the little time I had left of the round, I demonstrated just how legit it was to get on.

3. Can you and another player, for whom you two are both mutually suspicious of one another, KOS and then UNKOS each other as a way to know you two are survivors and can trust one another?

 

1.) No. KOS is just that: KOS. Purposely falsifying it will result in a ban. Using KOS for ANYTHING other than a KOS will result in a ban.

2.) In this example, it's TECHNICALLY allowed. That doesn't make it right, though. 9 out of 10 times, if survivors can't access the area, it's typically classified as an exploit... So, play it safe and don't use spots unless everyone can access them. If you get votekicked for sniping from here as a survivor, do not be surprised if you get votekicked for glitching.

3.) No. See answer #1. Only use KOS if you're sure they are infected. KOS is 100% certainty no matter what. If you're suspicious, call a "SUS," just like with anyone else.

EDIT: Added statement after #2

 

Well okay, but can you get Marvel to confirm this? He is the owner, after all.

 

No. If my answer isn't good enough and you want to shake down the owner over it, you get him to respond.

 

Roland's right. If the spot is not accessible by survivors, just don't use it.