The easiest way would be to upgrade to Mac OS X 10.8.2 and Aperture 3.4.3 with iPhoto 9.4.2 and to convert your Aperture library to the new unified format, see: Aperture 3.3: Using a unified photo library with iPhoto and Aperture
This way iPhoto can open the Aperture library and use it as iPhoto Library. Your original images and edited image version will still be paired in iPhoto, the keywords and captions will be available.
All other ways to go back (with Aperture 3.2.4) would mean, that you will have to export the edited versions and the original master image files, and when you import them to iPhoto you will have masters and edited versions as duplicate image files. You will lose the lossless workflow. So you would probably have to decide for each individual image, if you prefer to keep the original, the edited version, or both.
Thanks leonieDF for your suggestion. That would be the easiest way of dealing with my file, & I may be forced to do so by borrowing use on another machine. Neither my personal nor work budget allow a machine upgrade this year, & the MBP I have can't be upgraded beyond 10.6.8. (It's the computer I live with for both work and home.) In another 7 months I hope to migrate to newer hardware. My photo files/libraries I've kept on an external HD. Have over 15K of images. After this experience I will modify my work flow so I'll have a separate file of the images saved as TIFF as my lifeboat, and will likely move to a referenced file instead of managed file in the future.
You wouldn't have any inkling as to how to salvage my Aperture relationship would you?