@comiclab hey, no problem (: Around 2.3 MB or so is the most the forum will take without resizing.
@gavnarrr well, the concept art should match the illustration. The judges wont go nitpicking every detail, but having too different concept art just defeats the purpose of having it at all.
As for the render - you don't have to render both views in 100% meticulous detail, but don't forget that it's just as much part of the submission as the final image. Having the concept sheet look undone will probably not look well.
Look at last war contestants (and winners) to find that neat spot in the middle