Can I tell iPhoto to store photos in one directory within the library? When I add photos to iPhoto 11, it copies them into its internal database. This is good, but it creates a bunch of numbered folders. Is there a way for me to tell iPhoto not to do that, and to just use one folder for all the photos?

That way, when I want to access the photos directly, say to upload to Google+, I don't have to collect them from multiple folders.

I could use iPhoto's Export function, but that apparently insists on re-encoding the photos :( This naturally decreases quality and increases file size (if you choose the Maximum quality setting).

Lightroom, for example, gives me control over where the files are actually stored. The storage is still managed by Lightroom, but I can tell it to store all my photos in one directory, in this case.
No. iPhoto does not allow you to dictate the internal storage scheme. However, the export function does have an option to export the original file, so you can avoid the re sampling and/or format conversion if that is enough to stick with what you have. Additionally, Aperture and iPhoto can use the same storage, so you could get aperture and do the following;


convert the storage of any photos you want to folders and then save the library. 
continue to use iPhoto for convenient tasks and iPhoto will work with the aperture store locations. 
do all imports in aperture when you want the originals stored in specific folders. 


You can use Lightroom, PhotoMechanic or Aperture which all allow whatever folder based storage of photos you prefer.