I would like to point out that I messed up on point 6 - what I meant was completely different but I formulated my thoughts badly. Let my try again.
The problem with notifications is not that they have different priority (which is OK when used with good measure), but they follow three completely different schemes.
The voice notifications are often too vague when warning the player about problems and can even mislead the player, giving him a wrong idea on which problem to concentrate his efforts.
Players that play the game without sound (which would be a shame, because they will miss out the great music) will not receive these notifications.
You are completely right, however, that they offer the player flavor and immersion, but at most they should have been reserved for messages like “You have been in power for more than 10 years Presidente”.
The notifications in the circle menu are the most problematic ones, as they can be lost if the player through accident or design selects one of his units which closes the information and it may be hard to receive that information again. Information about election polls, coups or uprisings is crucial and it should be present at all times while these events are relevant.
The memos occasionally offer information that is not relevant enough to justify breaking the game flow (I felt annoyed when I received some a notification about the price of goat products in the middle of a bloody uprising).
What I find messy about the notification system is that the rules by which the notifications are prioritized and presented are strange and occasionally illogical. I strongly suspect that some of these decisions were made as a result of technical limitations rather than by design.
My remark about the unified system was stupid (I added number 6 as an afterthought). What I meant was that the different notifications should be incorporated in a unified interface like the circle interface is connected intrinsically to the build/edict/overlay menu.
Now on to your other comments

When I say that the interface is too big, I mean that there is too much space that is not directly used for providing information (too much blank space). A third of the screen is covered in a brick wall which should have been at least three rows shorter. Again, this might have been a technical thing, as the interface is not updated as often as the main window, thus improving the frame rate.
What you are suggesting is that the developers / designers are better able to determine what is vital information for all players.
The sad truth is that developers / designers are not better able to determine what information is vital for all players, but we have to… User-customizable shortcuts are a great idea, but only experienced players will actually benefit from it. New players do not know what information they need, so they will use the interface as it is. The interface greatly affects how a game looks, feels and plays – if the player experience is marred by not knowing where to click, or not knowing how to do what they want do, they might throw away the game without ever really giving it a chance.
I don't see that "scattering" as a bad thing. For one thing, the MAIN WINDOW or MAP is the primary "interface"; therefore it is desireable to allow the play to see as much of it as possible. That might mean that the Central Control Panel should become a "pop-up"; The Map Navagation Area and the Circle Window might become suppressible, separately.
What I meant was that there are too many different control schemes in too many different places. For example, firing people, upgrading, changing wages and work modes are all in the same screen but each is done differently (the work mode is changed by a drop-down menu, the wages are set by clicking on a bar, people are fired by pressing a key + mouse click and the upgrades are done through buttons).
Thank you very much for sharing these comments with us! I hope that my rejoinders may be helpful to you.
Player input is always good. I theorize too much (you might have noticed

) and rejoinders like that bring me back to the real world with the real issues.