2. A power chord with the octave in it is still a power chord. Yes it sounds different, but that doesn't come into play when naming chords. A and A7 are different chords because they have different notes in them.
If we take A major (A, C# and E) and rearrange the order of the notes so it reads C#, A, E is it still an A major chord? Of course it is! Does it sound different to the root position chord? You bet.
Your formulas for power chords are correct though.
