1) Who is doing the most talking, you company spokesperson or your PR person? Should be the former, rather than the latter. Unless there’s something majorly going south in the briefing, a PR person should be seen rather than heard during the course of a briefing.
2) Hospitality: Sure, food is nice to have, but the best thing to have on hand during a one-on-one chat is a drink, preferably water. And this goes double if you are conducting briefings in Las Vegas, home of the dry throat and parched mouth.
3) Twenty-five minutes or less, if you please, depending on the topic. Unless you have some really juicy topics (note the multiple) of interest.
Can’t you just “out” whoever is out there speaking at trade shows – particularly when they are NOT the spokesperson? People need to know that’s not a “good look.”