The back button breaking seems to be if you're not logged in, as loading the dashboard redirects to the homepage. Might be better to show a modal or something prompting the user to log in or at least use window.location.replace so it doesn't kill the back button.
The demo page looks to be what I was missing, are these placed in a specific location (eg the bottom right corner of the window) or is that up to the site owner?
There is no green light at the start - it's the lights going out they react to. There's also no minimum time, you can get moving after 1ms - it's legal. In fact, you can move before the lights go out, there's a tolerance before you're classed as moving.
The demo page looks to be what I was missing, are these placed in a specific location (eg the bottom right corner of the window) or is that up to the site owner?