The Hue Bridge can do #1 on its own, but I don't think it's exposed with the stock app. You can set up a sunrise/sunset trigger based on your geographical location - I use this to turn my outside lights on and off.
I did it manually, using the debug web page[0] on the bridge to set up the "light sensor"[1], which is really a calculation of sunrise and sunset based on your location.
It takes a few hoops to get the bridge to generate a username and craft the appropriate JSON to set everything up, but Philips has really good documentation on this.
