A static model would mean something that does not move. As long as you don't get into the habit of having large amounts of polygons sitting inside of your model you'll be okay.
Can i allow polygons to "end up" inside the character? Like when i make hair i want the hair to be close to the head.. which makes some parts go inside the head..i heard that it's bad.. ( idk if it only apply to 3d printing ). This drive me nuts.. since i try to avoid it at all costs and it limits me greatly