Sounds interesting, but your summer schedule will not go right with me.
Two points I'd like to comment, though:
most nations will also be able to recruit armies directly from their population, without a gold cost
I think this is a good idea. Militia shouldn't cost anythig and Doviello, Clan, Hippus are warlike enough that they should probably be able to field decent armies at any time. Luchuirp, on the other hand...
Regarding secrecy:
As for characters, I won't even reveal what characters exist or who controls them - that will be something for that player to choose to reveal.
Do you know how many PMs I got in FFH NES Ii about who I might be?
People have thought I might be the Labyrinth, wanted to know whether I played an individual or a group, wanted to know if we were on the same continent, if I was the stewards od iniquity, plainly asked who or what am I, made wild guesses like Kylorin, Cassiel or a vampire. Some contacted me without even being able to contact me IC.
I ended up giving some orders and writing some stuff so it would be clear that I could be contacted IC. That's slightly out of character, because my character is kind of, not very sociable(?). but I felt it was necessary.
So you should know that players with anonymous characters, particularly if they present their character's actions in, let's say, indirect ways, are going to be asked a lot of things, most of them OOC. This will make secrecy somewhat annoying. It's both very fun and at the same time you can't realistically be contacted.
So, from a story point of view, I think people who want to contact anonymous characters should find some ideas in order to do so, and not use a cop-out like "magic".
Why?
Because it should be possible to fail.
You try to contact someone in the slums, but you don't really know who that person may be. Maybe you'll be contacting someone else. Maybe someone else will eavesdrop you. Maybe someone will hear you and make you think you were talking to A when you"re actually talking to B.
Lots of possibility for subterfuge there. However, if players communicate by PM directly, this doesn't work.
So orange, think about this a little bit. In your typical NES, nation A can't easily get nation B to attack nation C by faking an attack of C against B, because the players are very likely to see through it OOC. Secrecy is fun, but you'll need to manage it and help players play secretely or setup subterfuges.