I'm thinking I should do the PC cord extension and get the ebay setup.
That would be a good starting setup. For what PocketWizards cost, I think there are more fruitful investments for a hobbyist.
17mm on your 20D is equivalent to the field of view of about 27mm on a full frame camera. So the Vivitar will cover that without any additional modifiers.
The Stofen Omni-Bounce can work well in some situations, but there are other methods that work just as well. When you start bouncing the flash, an index card and rubber band will be quite useful.

