Just as long as you can see the stripes on the rendered unit, it should be fine. You'd have to shrink your model down to the proper scale to check that...
As far as a MG goes, it's up to you. You're talking about a MG mounted on the top for the commander to fire, right? That might look nice, but it really would just be decoration.
As far as a MG goes, it's up to you. You're talking about a MG mounted on the top for the commander to fire, right? That might look nice, but it really would just be decoration.