Here are a few tips that make everything easier, mostly from demoing at PAX several times (at the GtG booth). apologies if you already know any of this.
You've got good ideas about what to bring with you. Those things will all make it easier.
Be sure to take care of your throat. the cons I've been to are uniformly loud, so you have to talk loud to be heard. Even if its a quiet one, throat lozenges and water (or tea) are good if you are going to be demoing for any extended period of time.
Shower. Use soap. Wear deoderant. I'm sure you do all these things already.
Hero Selection
Its really, really, REALLY useful to stick to a limited selection of heroes. Christopher encourages pulling out a few decks and having them sit on the table to give the impression that these heroes are for picking...regardless of the ones left in the box. Focusing on heroes that are super-easy to pick up and play is essential, as it keeps the turns ticking and complicated rule questions to a minimum.
Legacy, Ra, Expatriette, Haka, Tempest, Fanatic are all great picks, as they are very easy to pick up and play, but have some cool combinations and tricks that can make anyone feel great when they discover them. Fire blasts, shotgun-to-face, Haka-of-everything (and Savage mana), and lightning slash are all things that make people feel good.
Legacy is for you. Demoing the game is more about making sure everyone else is having a blast...and Legacy facilitates that better than any other hero. He makes games smoother, is easy to explain, introduces people to party support and the basics of a cooperative game, and occasionally hits super hard. If someone else wants to play Legacy, awesome!
You will get people (you might be that person) who want to play Unity, Omnitron-X, or the Argent Adept. Where possible (and some people will insist), try to encourage them away from them. the reason is that Unity and Omni-X, and the Adept have long, complex turns...and during a con you want to keep everything running at speed.
If you get a group of veterans, or you've run an intro game and have no one waiting...then its time to break out the other heroes.
Villain Selection
Baron Blade is the way to go. You'll win more often than not, but he can have some surprising twists. His shields and backlash fields introduce people to retribution damage (and can have some fun interactions with Ra's Flame barrier), as well as the beauty of destroying ongoings. His minions and devices give a good introduction to other targets within the villain deck. since he and Legacy are Nemeses, its a good introduction to that system as well.
I've heard varied ways of setting him up, but one that I agree with is to pull 2 of his Mobile Defense Platforms (MDP's) completely out of the deck (or secretly put them aside and then on the bottom after setup). This leaves him with just his one MDP and speeds up his flip condition (and makes winning more likely). There are people who get frustrated at losing, or even when they perceive a setback in their progress, and Con conditions can cause tempers/frustrations/emotions to run a bit higher than normal.
Give your players the best shot at winning. Then come back with a harder fight when they stick around!
Citizen Dawn or Voss are good follow-ups from the core set, or you could go with a fast, brutal fight with someone like Apostate.
Environment selection
Insula Primalis is the way to go. Its got dinosaurs, perilous Lava, and the potential for massive damage increase with the Obsidian fields.
Hope you have a great time!