1) A matter of taste. I personally prefer the fixed KB system, as we would need a bar showing the turns with the HoMM5 system and it gets confusing. That system works well for an RPG like Final Fantasy, but not HoMM-style fights in my opinion.
I wouldn't mind the Hero getting in a bit more on the action though.
2) I definitely agree on this. More starting options and viable troops would be great.
3) I really like this idea. It's annoying how we constantly have to go back to the outskirts to restock.
4) Great idea.
5) Not really necessary, but not a bad addition.
6) I'm pretty sure that the reason for this is that units of variable size don't work very well on a 3d Hex grid. Boss monsters are an exception obviously.
HoMM3 had units of 2 hexes, but all fights were horizontal in nature. With 3D battlegrounds, it could get confusing.
It works in HoMM5 because they use square grids, but that has its own problems.
7,
Good suggestions