I'm going to be buying quinoa flour and wanted to use it to make up pasta. Is this a direct flour replacement in a typical pasta recipe or are there other changes you need to make?
In the pastas that I have made the structure of the noodle is built out of protein- usually entirely from gluten from wheat flour. In fact the base of my pasta is just flour and water (or juice or pureed vegetables, etc.) Egg noodles, obviously get structure from the egg.
Quinoa has no gluten and will impart no structure to a typical pasta.
You could easily add it to a normal pasta recipe as long as it was not in so high a concentration as to compromise the gluten structure. Without experimenting I don't know what ratio this would be.
A cursory google search found several quinoa pasta recipes. The ones I looked at were similar in that they relied on a variety of starches and egg for structure. I imagine these would taste fine but they would be more like dumplings or egg noodles than al dente Italian pasta.
The results of the quick search: