As for the copyright thing, just contact Microsoft and Bungie and ask them about it. I am guessing that they will be ok because there is no game (in the makes as far as we know) that incorporates space tactical combat in the halo universe. As for the UNSC Super Carrier, I am currently modeling it, when I am about half way done with it I will post the original drawing as kind of a teaser. In addition to this if you need me to model the C709 Longsword-class Interceptor, I will happily do so. Please tell me if I can model anything for the UNSC side and I will be happy to do so.
P.S. I can not texture, well at least not very good, so I will just have to send you the 3-D files from XSI