This is all solid advice, some of it shouldn't have to be given. Gum? That person ought not even show up. I am compulsively early to meetings, so 1/2 hour wouldn't cut it for me. If it's something I really want, I'll be there an hour in advance. That gives me plenty of parking lot time to get in the proper headspace. Best piece of advice you gave, only because I think it's the most often overlooked, is the bit about not getting a haircut, wearing a new suit, shoes etc. You want to be comfortable and confident. You don't want to seem like a penny that only gets shined once a year. Good stuff dashnhammit!
(happy leap, then a bow, then a smile) Thank you! edit: as for the gum chewing, that's one of the comically awful stories I've heard from companies doing the interviewing. Some examples (wish I could find a better compilation, though): http://www.workopolis.com/content/advice/article/recruiters-share-their-true-job-interview-horror-stories/