The chalky priming could be from the temperature you sprayed the can, or maybe not shaking the can long enough. Just a few seconds may not do it. The other possibility would be the defective can, possibly because it's been sitting on the shelf for so long (I'm thinking years, anything less, you could probably just shake the can even longer).
Your blending looks really good on all of them.
On the dragon, I would recommend filling in those gaps (neck and body) with some perfect plastic putty or something to get rid of the seam. I also noticed what looks like speckling from the airbrush. I would suggest raising the PSI to around 30-35 to eliminate that.