but I can't figure out how to drag OUT only file export if you want the original quality
What's "original quality", exactly? There is no version of iPhoto, Aperture or Photos that reliably yielded a copy of the original by drag and drop. Drag and drop was always (and continues to be) designed to use the preview version of the image. This is a medium quality version of the image.
"Always up to date" is unclear. You'd be surprised what people call 'up-to-date'. Best to tell us the versions you have.
Bearing in mind the above:
I can drag an image from the Photos window to Messages app. Without knowing what versions of these app you have there's not more to be said. It works. I get a preview of the image in the Messages window.
There is no version of iPhoto or Photos (nor indeed Aperture) that used drag and drop to bring the image to an editor. In iPhoto, you used the External editor option, and in Photos you use the Extensions module in the Edit pane. As Photoshop - and note this is a decision by Adobe - does not support extensions, you'll need to purchase the External Editors extension from the App Store. it's cheap: https://itunes.apple.com/ie/app/external-editors-for-photos/id1074021862?mt=12
Again, there is no version of iPhoto or Photos (nor indeed Aperture) that used drag and drop to bring a full quality image to Illustrator. Never was. Export, like you had to do in the other apps.
Mail: Drag from the Photos Window works. As does Share to, as does the Media Browser.
so far my only resort has been screen shot to desktop OR screenshot to clipboard > paste.
Neither of these will result in anything remotely like a full quality version of the image.