All of these questions are answered and more in an article by Leonard Fischer and Gannett News Service at Detnews.com. They have interviewed Jason Snell, editorial director of Macworld magazine on just what the switch to Intel means for Mac users. Here is just a little of what he had to say:
You probably won't have to consider buying a Mac with an Intel processor for the next several years because Apple is making a gradual transition to Intel, Snell says. "Apple is not going to stop making some PowerPC systems until late 2007. They say the next version of OS X (called Leopard) won't be out until around then, and that version will run on PowerPC systems." Whether subsequent OS X releases will run on PowerPC isn't clear yet, but Snell says Apple will provide "OS X mileposts where you can see the obsolescence of your computer coming, but if you have a relatively new Mac, you don't need to worry."