Your questions made sense, but my answer probably won't help. It's entirely up to you! Some people enjoy quilting, some people don't.
My preference is to quilt rather densely, even by hand. I use backgrounds that I feel will compliment the main design without overwhelming it, but will still allow me to finish the quilt in my lifetime. I also choose solid fabrics, or nearly solid fabrics, so the quilting will show up.
The only rule of thumb is that the quilting should be dense enough for the batting you're using...in other words, if the batting package says there should be a quilting line every 2 inches, then you know you have to do at least that much quilting.
Janet