Thank you for the detailed feedback! I completely agree on the resource icons and it's something I'm planning to do... I just haven't drawn the icons just yet :D
Showing stacks of units in the Units section is an interesting idea but actually, don't you think showing an icon of the unit and its number would be better? Because I feel like if I only showed stacks of units, then you could argue that the game doesn't tell you EXACTLY how many units you have and it would lead to frustration.
I love the idea of showing whether you can buy an upgrade or not. I wrote down all of these ideas and I'll implement them. Thank you so much. :)