I'm not sure "common" is the right word. I've met people who have other dreammates, for a lack of better term, and others who don't. It's kind of luck of the draw, I guess. Who decides to sign on and who doesn't.
If the strange things that happen require fighting, then I fight them. Especially when they threaten my students.
So do I. My family is very important to me.
I think its more by design. My sister and I were named for two figures in Norse mythology: Huginn and Muninn. In the Dreams I got the name because crows are considered bad luck. At least that what the dream version of me says. Why it's spelled with a Q and not a C, I couldn't tell you either way.