Gamestudio itself is a PhysX application, so you can test it on different computers. A compiled EXE alone will certainly not work when you do not add the driver.

PhysX accesses nVidia hardware and under Windows you always need a driver for accessing hardware. I dont think that the video driver that you install with your nVidia card will be enough.

There are lots of PhysX titles out, many new games use PhysX, its the main physics engine. Personally I dont see any problem with the driver, but this is mostly a matter of taste.