Coding Camel

It's definitely possible, just how is the question. From experience, I've been able to run a batch file more than once, and have multiple servers go up. You should be able to have 5-6 batch files routing to different CFG folders, which you can run out of the same arma 2 directory. I'm not entirely sure how you run servers on different IP's from the same box, although it's fairly simple i'm sure.

I'm a firm believer in windows, I would stick with WS2008, great OS for arma.

I assume you mean the in-game admin tool, as so many make the mistake and install... Most missions will have it built in already, just look around.

I really cannot suggest starting a server on your own, as you are obviously new to the game, and scripting within it.... I would highly suggest joining a community running takistan life, and go from there. Most people are fairly helpful, and will let you do development work in their communities.