Does online backup work well for OSX?
The data returned from Backblaze ought to be correctly recognised by the Mac. Folders like iPhoto have a special structure that the Mac shows you as a single file, but in reality it is just a folder.
In the same way, Applications are, in fact, folders too - but the Mac hides the structure from you by default.
This is what your iPhoto Library looks like on Backblaze…

When you get your drive, you may have to point iPhoto &amp; similar apps [Aperture, iMovie, Final Cut Pro all have similar structures for their Libraries] to that 'folder' initially, but it should then be treated as your regular Library.
Edit:
I just tested this empirically by downloading my entire iPhoto Library from Backblaze.
When it arrived, it was in its original disk/folder hierarchy; so had that been an emergency situation I could have copied the entire structure right back to where it came from.
Initially, it looked like a regular folder, but [a step you may not need to take if everything is restored to its original locations] launching iPhoto with the  Opt ⌥  key down to choose a new Library &amp; selecting that folder - as soon as it had finished loading to iPhoto, the 'proper' iPhoto Library icon &amp; 'hidden' structure was restored to it.