When I'm growing a mullet I want to know should I be getting that quarter to half an inch cut off the back when I'm getting my hair cut or should I NOT get the back trimmed at all?

It depends on the type of Mullet you want. If it is a ponytail mullet then you don't cut the back at all. If it is the classic mullet then you will cut the back in layers. And if you are asking if you should just get a trim then you should cut the ends to keep your hair in good condition.