Wow, the plot thickens! Yes, like everyone else I have to assume that Imp is Mr. Mxyzptlk. I think you've given us enough hints for that. And extra points for using him - he's a villain that just doesn't get used very often in L&C fanfic!
Interesting speculation on the clothes - the other posters all said it better than I could. I'm looking forward to see what the worst possible time for the spell to be broken is. Of course, the spell will break at that moment.
Thanks for making a very plausible reason as to why no one would recognize Gawain as the princess. I'd like to think that Clarkent is a little more observant and he'd pick up on a disguise of just a clothing change and a hat. After all, he isn't galactically stupid.
