1. By easier I meant smoother, faster, or more varied. This is because they increase very slowly in comparison to morale. Maybe if morale was nerfed instead, it would feel closer, but at this point increasing prosperity and prestige is just pure grinding. And sure, low prestige is inconsequential, but I'm sure that will change.
2. Again, this is in comparison to endgame. In the current update, the value of things is of course much higher. You can lend from the bank, but I lended the max to test it and although it's doable to pay the bank back no problem, it really showed me that the war takes a crack ton of cash. One way you can implement this is instead of 10* directly, 10* can be the max and the rate scales based on story progress and/or weeks.
4. So the way I was looking at it is that since the kingdom does not actually produce anything itself, it would be easier to become the imperial seat and purely manage international affairs, while giving each territory enough autonomy to fully operate its local affairs. This was a possibility I figured could be done if the Queen wants to stand her ground against the rival empire without wanting to keep micromanaging her lands at the same time. Similarly, the desert kingdom could become a protectorate if it wants protection against the rival empire, but this would require the Empress Route aka Badass Queen asserting her power enough for the desert kingdom to not ally with the enemy instead. This would be a Prestige heavy route.