Unit groups

If there is a stack, there should be an option to make it a group by a combination of keys such as ctrl+1, then when you press 1 it selects said group, eliminates much micro this way.

Yep, this is also been used in much more other strategy games. This could be a good idea for winning some time in AW. The only problem is (i think), that you are constantly changing the amount of a certain attack group. For example:
I have a group of 10units, and will attack a certain city. The next turn, i will have just 4units left and i will add new reinforcements from the city i just captured.. This will repeat every turn most times, so the time winning will be about 0.

I thought it as you have the 10 units, attack, leave 4, put reinforcements in the same stack and press ctrl+1 again to refresh the group and now you have group 1 reinforced.

The problem here is the AW doesn't track individual units, only types and amounts. So, if you have 5 infantry in a stack and add 5 more, there's no way to tell which ones are old and which are new. AW stacks are incredibly unstable - new units get added and killed (no problem, can still be the same stack), stack gets split (what happens if you take exactly half units out of the stack - which one is the main now?), stack gets merged with another (what if both were marked as groups by the player?) and so on. It's a bit messy, you see.

Maybe lock the units in stack to not be able to be split and only allow units to be added? I don't know the inner workings of the coding, throwing out ideas.