Ok, several things.
1) What can Macs do for me that Windoze can't do?
I think this was covered pretty extensively already...
2) Why are Apple computers generally more expensive that PC based computers?
Macs aren't actually much more expensive than PC's. Think about it: you can get a PC for, what, $800? But what do you get for that? A boatload of crap, that's what. For all the high-end goodies, you have to pay more. And for Mac-like quality and devotion, you have to pay more than most Macs for a computer like Falcon. Also, factor in the cost of troubleshooting: for most Macs, it is very low, but for most PC's troubleshooting costs can soar. The initial price of a computer is not all that you pay for; in the long run, Macs are much cheaper than their wannabes.
3) Is MAC OS X similar to UNIX? I believe so but tell me if I'm wrong. Does it have less functionality/features?
Mac OS X
is UNIX, just with a (beautiful, stunning, highly functional) graphic user interface. This has been ground into dev/null...
4) Is there a significant increase in performance between the G3 (high end) and the G4 (low end)?
This has also been pretty well covered... But I do want to say that if you want to compare hardware on the Powerbooks, go to
http://www.apple.com/powerbook/specs.html and check out the specs. Each of the PB's has a video out option, and all Macs I believe can output to a VGA monitor (which is all a PC monitor is, after all). As long as you're looking for a PB, look here.
5) Why are Mac computers performance rated lower than PCs yet cost more? Is it because of the software bundles that come with the computer?
The (relatively-see above) high cost of Macs has to do with the (I'll be frank) monopoly Apple has on the Mac market, the quality that goes into each and every computer, the generous software that comes with each computer, and the fact that Apple tends to overcharge stuff a bit. The only places that Macs are rated lower than PC's is in half-assed PC magazines.