Most of these can be found in the user's guide that's available here: User's Guide
Taking a screenshot:
While using the device, you can capture an image of a screen. While pressing and holding [BACK], press the Home key. The image will be saved in Gallery
Quickly adjusting the brightness:
You can quickly adjust the display brightness by scrolling left or right on the indicator line of the screen.
Activate your phone's mobile tracker:
If someone inserts a new SIM or USIM card in your device, the mobile tracker feature will automatically send the contact number to specified recipients to help you locate and recover your device.
That's it for now, I hope to dig up some more soon and I'll update the page as I discover them.