My god is that gorgeous
I know where my next kit is coming from!
Excellent work Reza
As for primer thats a tricky one, the oily nature of the plastic means you'll struggle to get much that will adhere completely. god knows I've tried !
It depends how much weathering you plan on doing though if you just want a few subtle chips here and there then it may be best to prime.
Otherwise I would just go for it with the main color.