Exgratia & All -I hate to keep doing this, but there's a book on this very topic. It's The Insider's Guide to Getting a Big Firm Job.Thane.
Is this a flame? Wear that if you want to stand out in a bad way. The fact that you even have to ask means you probably shouldn't.No pocket squares for interviews. Plain white or plain light blue are the only color shirts you should wear to an interview.
I don't know the first thing about buying suits. Can interviewers tell if it's a cheapy (i.e. <200)? Also, are navy pinstipes not conservative enough? I went into the store and asked for something conservative and that's what they gave me.