As i've been informed recently, i AM part of the team (yay!) and i take it upon my self to test you and help you out.
More custom models would be better, so, here's your "test". Make a prop, something complex (not very) yet usefull that may fit into multiple environments or places where the imperium is positioned. My best bet is to visit sites like
http://www.forgeworld.co.uk/ and
http://www.games-workshop.com/gws/ to find stuff that you wanna model. Select some stuff from those sites, and link them here, ill tell ya if we need them (remember, no characters). Once we've decided on the model, you'll start modeling it, and then uv mapping it as well. Ill try to help you as best as i can a long the way. If the model you make is good, we just might use it in the mod.
Now, regarding the specs of the model, the Tri limit is dependat on what your gonna make. So if a model is to be used ALOT in a map, make sure it has less detail, and if it wont be used alot in a map, more detail. But dont worry bout the tri limit just now, select the what you're gonna model, from there we will see what we got.
Hope this helps, and good luck. Awaiting your Response (Use this thread for now, no need to make another one)