As for the controls, a tutorial is planned for the future but there isn't one yet. In short, hang glider is controlled by weight shift. It's similar to rocking a boat. If you shift your weight to one side the glider leans to that side and starts turning. Leaning forward makes it dive and gain speed, and backwards makes it climb and loose speed like going up hill. Keep the speed above 40kph and enjoy! :)
Yes, familiar from flying hang gliders in real world. My instinct was to use mouse as per this and Hangsim, ie move the mouse as I would the basebar. I think that is how intended here as well, once get frame rate up!
BTW any possibility of a more pilots eyes view option ? Could just be a selectable position closer in and below the hang point.
All looks great, wish you success in your dev!