What ends up in the game engine is triangulated. You can use whatever works best for you. Quads are great because it allows for easier selection of rings and loops. Tris are often great for organic forms. You might want to force triangulate a non-planar quad that might be auto-triangulated in the wrong direction. afaik,…
It's a good concept, but needs to be finished or properly scanned. A good concept is normally straight on front and side views, next to each other and all the features line up. This is the best kind of concept to get you rolling and actually build off of. They normally don't look "dynamic" but they work well for the 3D…