just a note - balance is more a question of the distribution of weight rather than size/volume. As can be seen from the image, the upper/tablet section is largely empty, and this is likely why the lower part, even if thinner, has roughly the same weight as the upper one. So, unless the lower part's center of gravity is close to the hinge, it can be quite stable. 3g - with the internal slots, this not really a question, you can stick in any usb 3g dongle with linux support. same for additional bt/wifi/gps stuff. these internal slots are in a sense a poor man's cardbus slot