Right click and go into settings, and change storage to unlimited, so you don't risk losing saved games.
Also, Internet Explorer may cause keys to stick, you'll need to change some security settings, or use a different browser.
WASD or Arrow Keys to walk around, Space to interact. Mouse for everything else.
Sound and Quality settings in the right-click menu.
There's still probably a few bugs in there, so if you find something major, gimme as much info as possible about it.