the one on the edge of one corner, and the 'home' switch on the face, down for 3 or 4 secs simultaneously until the gadget shuts down and has to be re-started.
Indeed worth knowing, but your description of "has to be restarted" is incorrect. The action you describe is a hard restart. You will find that if you hold the buttons down, the Apple logo will re-appear and the device will boot as normal.
You can't mimic it on Windows, but on Linux or Mac, its the same as doing a forced reboot, i.e it immediately reboots the platform without invoking shutdown scripts first.
This apparently "re-sets" the iPad far more comprehensible than just 'swipe to power off' and gets rid of a lot of crap.
Not really. In the majority of circumstances, its just faster than a normal power-off because its a hard-restart rather than a clean shutdown.