It's for everyone and anyone - age/gender/orientation/race/style really doesn't matter. The aim is just to chill out and enjoy the show.
"Who are you?"
I'm a freelance web designer into all kinds of music but particularly fond of alternative indie stuff like The National or Future Islands
"Do I need to perform?"
Not at all, most people just come along to chill out and enjoy the show. It's mainly a social group.
"I want to play but I'm nervous about it. Is that okay?"
That's totally normal especially for beginners. You don't have to play but you can if you like as long as you book your own playing spot with the event. Personally, I always feel quite nervous about playing so I prefer to go first and get it out of the way ;-)
"Why is each event limited to around 10 people attending?"
Those numbers are just the people from our group! We're attending regular open mic events where lots of people are already going whether we show up or not. I'm limiting our numbers so that we don't risk flooding these events and preventing people from playing!