This is cool! I imagine this might be too far off your intended use case for now, but Rally feels really close to the perfect solution for live performances. Rather than breaking off into tables, you could use your "ambient sound" feature to lower the sound of all the audience members, so that you can enjoy the response of a crowd without drowning out the performers.
Agree with what has already been said (dont use company resources like a work laptop, dont work on it during typical work hours, dont build a product that might in any way compete with your employer, etc.)
As far as work contract goes, (I am NOT a lawyer, just based on experience), it's worth reading over and seeing what the language is around IP. Most states protect your right to build stuff on your own time (enables innovation, also you aren't the property of your company) making some more draconian contracts unenforceable. But it is always better to be proactive, rather than assuming a court battle will be unlikely because 1) who knows and 2) court is never cheap.
If you want to work on something and you are worried about the language in your contract, talk to your employer about the project and getting some form of written exception for it. Side projects generally make for more capable, satisfied employees, so if a company made a massive stink about literally owning anything you make anywhere in your life, I'd be very very wary, as that mindset is a scary sign.