Fellow Guitar Dudes always have my respect
I'm not sure what you mean with the original view, but whenever you're reviewing a picture, a half press of the shutter returns the screen to showing the basic settings (on my bodies it does, I don't have a K-70).
User modes are what you want them to be. If U3 comes pre-loaded with astro settings (as you're suggesting it does) then all you have to do is put the dial on U3 and you're ready to go. There's a menu option to override the user settings with whatever settings you have on at a given time.