I wonder if they could they be exported, transformed to mp3 and put back in the iPhone's VoiceMemo folder.
And even if this sounds like science fiction, i ask... could they at least be moved to a folder on my iMac so i can free space in my iPhone?
Your requirements are confusing. Do you want access to the files on your iPhone? Yes, you can get them to your computer via syncing but once you've deleted the copies on your iPhone you won't be able to hear them unless it's via a cloud service.