Recommend APs for meeting space? Looking at Ubiquity but which ones?

I am setting up a network in a 4,000 sq ft conference space. It normally has a few people there in offices. A few times a week there will be 50 - 125 people. We need to set up a network that provides public wifi but also protects our bandwidth for streaming the presentation to YouTube.

I have set up home and small office networks (ok, only a couple) with Ubiquiti hardware so I am comfortable with that but I don't know which APs to get for this size room and this many users. (All indoor. Only drywall to get through.)

Here are my questions:

• Will the Traffic Bandwidth Limits in UniFi allow a USG to limit how much bandwidth goes to the guest wifi network?
• Which APs should I go with?
• How many APs should I get?

I don't have illusions of giving everyone great bandwidth. But we want to protect what we need for production.

Thanks

Suggestions?