As far as I've seen most buttons are usually on the back of the Bios themselves. If you were good at wiring & electronics, you probably could run something like a Momentary switch to your gaunt that would stay on until you pressed it again.
As for cons - trust me. I've seen folks on here go to Anime cons, Dragon Con & beyond and every time I see posts or talk to the members Preds do very very well. Estelle was telling me the other day that Elkman's suit almost got torn up at Dragon Con so trust me, regardless of what con you go to, your pred suit will make a huge impression.