2) To each his own, I suppose, but I have conflicting anecdotal evidence. Hipmunk passes the "parents test" with all of our parents :) And as for "people who spend big bucks booking travel," I can point to the huge amount of email we receive from assistants who use us exclusively. Maybe we're not everything to everyone, but we're at least making some people very happy.
3) We do re-target quite a bit, and that's probably what you're seeing. Most of our growth has come organically, which again speaks to the fact that we actually do help people find planes / hotels in far less time than our competitors, including Expedia.