No, sorry, you can't. Adobe doesn't do that. Some people have been able to use the Report a Problem link on the receipt to cajole apple into letting them return it, but lately they seem to have gotten tired of doing that. Wouldn't hurt to try though.
As for working with iphoto you have two main options:
1. Set PSE as your external editor and send the photos from iphoto. Save, not Save As, without changing the name or format once you're through editing and iphoto will remember last saved edits + original, although you will lose the edits if you want to see the original again. To make this work you will need to go to the PSE preferences>saving files and set On First Save to save over existing.
2. Export the photos from iphoto, use file>Open in PSE, then make as many changes to name or format as you like. Import the saved images back to iphoto as new files.