1. I would like to have the normal view button at the ViewCube. I think this is the right place for it.
2. And it should have both functionality (as outside a sketch and as inside a sketch, accordingly what you are doing at this moment).
3. Additional funktion: First click will bring the view into normal view to the plane. And next click (if you have not changed/moved the view) will bring the view to anti-normal view, and next click back to normal, and so on.
Hope this is comprehensible.
Markus