Regarding Kaos, it is my personal opinion that he should be un-banned.
Few reasons:
To begin with he was an admin as far as i know? which would suggest that he was trusted by you to a high standard. I completely understand that he abused that trust and even abused his powers, but it was for fun. Now it makes sense why you should ban someone for such a thing, but it would be a better idea to demote and remove those powers that he was 'abusing'. This would mean he can still be around [as you enjoyed it thats how he made it to admin?] but also have the chance to prove him self
However i completely understand that while it was some 'fun' it doesnt justify what happened.
All in all because i dont know him any more than a couple of hours, but