As far as the terrain goes, it depends on what tileset you're using. Braxis Alpha, for example, is a tileset where, if you lower the terrain, it shows space like you mentioned.
For implementing old units, there is a mod called StarBow that already does that fairly effectively. Not sure if that has AI programmed into it, though. I think you can apply StarBow to your map by adding it as a dependency.
The things that you're looking for are fairly basic. Take a look at some of the tutorials around this site to see if they can help you out. And, of course, post questions to one of the development forums. You'll typically get an answer within a day or two depending on how complicated your question is.
Also, you might want to edit out your email address and have people PM you here instead. Security and all that. Because while the government most assuredly already knows more about you than you do, everyone else doesn't need that information. ;)