1) Agree totally! Maybe the normal level one would be left-clickable and the upper level one would come from right-clicking? Not sure, depends a little how normal it will be to cast spells as a higher level spell.
2) Yes! I was a little lost during the first couple of level ups, and that would make it so much easier. Maybe even organized by type of spell within the levels? Like evocations in a row, etc. (not sure if that's the case already, though)
3) Agree in a way, but not quite sure how much UI space that would take versus how other you will end up using the skills.
4) This would be awesome, and would work how it's intended as well. Some situations might be harder to cast the spell, meaning that you could get a disadvantage for example? Like if you are trying to vocally cast charm person in the middle of a pack of wizards.
My addition:
1) Would love if potions and scrolls would default to their own tab on the hotbar. The leveling up is so fast at the moment, that I literally forgot I got some new skill or spells because they were added to the second tab of the hotbar while the first tab was crowded with random drinks.
