Niteshade

My understanding is that you should use a polyester based filler because it doesn't shrink as it dries. For finishing touch there is a second type of primer that is even smoother and fills any imperfections in the first filler. The other consideration is that not all primers are compatible with all paints.

I am going through the same process right now but you seem to be a little bit ahead. I still getting the parts off the car and hope to pick up some stripper tomorrow. I suggest you consult a quality dealer and lay out a plan.