Syncing iOS photos to MacBook - Photo Stream behaviour?
Photo Stream only saves either your last 30 days' worth of photos or your last 1000 photos, whichever you hit first. However, in iPhoto on the Mac, the "automatic import" feature (which I believe is enabled by default) will automatically copy any photos in your photo stream to your Mac's local hard drive.


  So I think selecting "Photo Stream" in iPhoto shows the temp store, but they are also saved into a Event where they will remain even after being removed from Photo Stream.


Correct (again, as long as you have automatic import enabled. You can double-check the setting in iPhoto preferences).