I had to use the pink Battle portal button in the bottom right corner access the materials area for grinding. It was not accessible via the transport portal that brings up the map page in aerie.

As for the dragon, I used Queen P which worked fine. However, there is a time limit on the dragon in which you have to beat him in so many rounds if I remember right. So, you need a bit of firepower before you are just down to Queen P and Herja.