Hi CadianGateTroll, I think it's awesome you want to express yourself in a creative way by sculpting models. Yes, making things out of plastic putty is allowed and encouraged here. Unfortunately I think the things you are asking for information on, like specific dimensions of
GW models for the purpose of making your own sculpts, probably fall into the realm of recasting copyrighted models. The Dakka Dakka
FAQ goes into specifics on this subject. Here's a link:
http://www.dakkadakka.com/dakkaforum/posts/list/30/205120.page#8615594
Note: I'm not a Mod, just passing along information. Don't shoot the messenger.
With that being said, go forth and sculpt. Create. Have fun with it. Share pictures.