Physical mask could maybe be useful for tricking him into giving away info, but we'd have to know a lot about the person we're impersonating- plus if it's an alchemical preparation, it wouldn't give us much time for an interview. Clairvoyance probably won't be necessary to recon the restaurant, since it's open to the public after all, but a quick astral recon would be good. Maybe give it a look on the astral right now, and another once we drive over just to see if anything big has changed? Also an improved invisibility preparation or two would be really handy just in case this comes to a fight.
Also, the layout of the place might be publicly available without hacking- maybe there are photos and stuff. If not, an astral recon will give us the layout, although it won't be able to make out much in the way of technological devices.