all good points. I'd avoid alcohol, finger food, use the correct silverware, use correct table manners, etc. Be sure to take along a small pack of floss - just in case.
I've given interviews where lunch was involved and been interviewed where lunch or dinner was involved. I was once interviewed where the hiring manager ordered the most expensive things on the menu, ordered alcohol, didn't have the best table manners, etc. but that said he was president and owned the company.
When I have given interviews to someone I looked for clear signals - can the person make small talk - personal life (not wife, kids, the type of things you can't ask an interviewee, but hobbies, interests - be sure NOT to say cigars that might set off a red flag).