Use a plastic opening tool or spudger to pry out the battery from the bottom. If a plastic opening tool or spudger isn't available, your fingernails may work.
Use a flathead screwdriver, tweezers, a toothpick or dental tool to remove rubber covers on screen.
While doing so, please be sure to remove the rubber screw covers carefully. If they rip or get damaged, you may have to buy new ones. These are NOT required to seal up the console, but for aesthetic purposes and for keeping dirt and water out, you should (re)install the rubber screw covers.
Then using a #00 Phillips head screw driver to remove the screws beneath.
Unlike the DS Lite and later models, there is no reason to take apart the bottom portion of the original DS in order to remove the top screen. The first ten steps of this guide could be skipped.
Nope, Nintendo engineered the Lite as a refinement of the original. Therefore almost every component is different! Likely to become cheaper to manufacture.