Wear whatever you feel comfortable in, but it's better if it allows more freedom of movement than something like jeans.
I have no idea of the GPS location. I'm old fashioned and still use street names and descriptions.
We train outdoors, so it's technically in public but it tends to be in places other people don't use so much.
Youtube is full of videos of people moving in different ways, and that's pretty much all you can get from a video.
The youngest person at the junior basics sessions is about 9/10. The rest of the sessions generally range from about 15-30.
Trying to be a helping hand from NorthernParkour and the British Parkour Coaching Association