(Sorry all--slow response time.) Does it have to be red quinoa? Please help me understand the differences between the quinoa varieties. I am using...

Quinoa is actually a seed (grains are technically seeds too but that's another discussion). There are subtle flavor differences between white, black, red etc. but I usually consider the color in terms of presentation. For example black quinoa looks quite handsome stuffed into a roasted red pepper. I like the red quite a bit but I wouldn't hesitate to substitute.