Thanks to the bastardisation the Unreal Engine, we typically find that windows servers (while more costly and resource consuming than nix equiv) are more stable. That is to say that the crash often as opposed to very often.
Which is a shame - the older servers like l4d were nice linux ones and generally (aside from l4d bugs) behaved themselves well.
As for the chiv servers, there should never be an IP conflict. Some info is passed between the various servers over something like a qinq vlan, some stuff passed internally (sql instance) and some stuff like master stats passed externally.
Btw the intermittant periods of freezing we see normally relate to a full stats update being pulled from the master stats. The more players there are on the server the more impact this has (and it's not bandwidth, it's tends to be massive delays in handshaking and uptake)- nothing we can control
The game servers don't really have much in the way of attack vectors; usually there people trying to use json rcon type stuff (which the server monitoring alerts on many failed connections in a short time, by log shipping and parsing, sadly) or by ddos attacks. The latter usually by ragey kids who got themselves banned, they don't normally amount to much or for very long, but there are some alternate ip pools we can use if need be. (had to change the IP's around 6 months ago due to some persistant trolling
)
The ids stuff mainly relates to the website; we used to get a lot of automated and actual attempts here (although 95% of the time are skiddies or people trying the odd sql injection). Not so much of either these days.
@5: I've heard good things about mint, so might give it a go. Especially since there seems a nice version of xcfe