In answer to your second question, I think you are saying that when you have a face, you scale it inwards first, and you want to then extrude outward, without pulling the new, smaller edge faces with it. If that is the case, once you have scaled your face smaller (or larger) just press the 'g' key, this is the default command for redoing the last action, and it will perform a new extrude face on the new, resized polygon. Or if you do something in between, just select that face again, and use the Extrude Faces tool again.
But I might have misunderstood your question.
Hope this helps