I think the one of the reasons for this is that there is no buffer. A lot of inexpensive cameras will do this kind of thing. You actually see the effect will previewing - how the images bends as you move the camera. My Aiptek video recorder does the same thing in the pictures and the even in the videos.
As to the shutter going off unexpectedly, it doesn't trigger until you let go of the button. I have had good results by holding the button and then letting go when I want t snap the picture.