1. You can conceal yourself in different ways. You can use "bounce" to go through several servers before connecting to your target. Also, you should start searching for higher level log deleters. The current top undeleter in game is a v27. Finding something higher than that and you can keep your self safe.
2. I have 8 servers and I do not get confused between the different servers. Each server would be assigned a number. You can differentiate the servers with the number assigned to it. If you have gold account you can even rename your servers.
3. When you come under attack, you can counter attack
4. The most probable reason is that someone deleted the file on the server.
5. MOST importantly, do not install revelation virii!! The virii can cause everything to be reset, and everyone will start as a beginner again. Many people do not like this, including me. You will get yourself attacked by many people for that. Of course playing friendly is nice, but there really isn't any rule per se. Just be sure to cover your tracks.