I use air erasable markers and the marks totally disappear without washing. I have about 30 minutes of clear markings and some marks will remain for longer but after a day or so are totally gone. My favorite is Leonis brand that I order through Amazon. I've never had issues with them but would test them on an inconspicuous area of older fabric first.
As far as how to quilt them design wise for me it would depend on what the pattern was. I do a lot of curvy quilting with a walking foot so painter's tape wouldn't work for anything other than straight line unless you cut it to a curved pattern which seems like a lot of work to me. Perhaps posting some pictures could give us some ideas.