Yep, I used a similar script launched by FKey to do the same job in OS3.9. As for the first question, I remember an app that used to do some real-time raytracing of a bumpmap onto the background, using the mouse as a lightsource. It made for an awesome clock in the middle of your Workbench screen
WBBump I think it was called, and wasn't an animated background per se but a borderless window sitting at the back. Good effect though!