The new iCloud Photo Library currently in beta is what answers your question. It keeps the master library in the cloud, and deleting a photo on one device deletes it everywhere. It has no time limit for storing photos, but it does use your iCloud storage space. Unfortunately, as far as I know, Aperture will never work with Photo Library. There is a separate app in development to replace iPhoto that sounds like it'll be your only point of access from a Mac app. As for Photo Stream, it only holds your last 30 days of photos in what is basically a transient album in the cloud. The auto-import setting you have enabled downloads each new photo that shows up in Photo Stream into your local library so that you can keep it beyond the 30 days when it gets automatically removed from the cloud. So whereas Photo Library acts like IMAP email, keeping your master list in the cloud with it syncing down to devices from there, Photo Stream is like POP email, the iPhone pushes the photo to the cloud, where it gets pushed to your other devices for 30 days and then goes away unless you saved it locally in that time. Not really a perfect analogy, but it's how I look at it.