I read your post, and I should tell you some stuff.
I can see your problems with EW4, though I have a found a way to circumvent these problems.
Yes, I have gone quite a bit of the first campaigns without generals. All you need is patience, skill, and some time before you can get generals. It took me half of both campaigns and quite a while before I even got Sulkoski and Dobeln!
As for princesses, there are some unlock requirements that are posted around the forum. Good hunting.
I would think that every game has difficult campaigns, and people should be able to agree with me. As I said, patience and time.
Yes, while conquests are slow, I found a way to circumvent the boredom. I've always liked the Downfall parodies, and I always seem to put in an Napoleonic setting and for the enemy. Example: "Sir, the [insert country you are playing as] has taken over [insert country conquered]." Somehow, that entertains me. I hope that you are able to find that entertaining spot if you do come back to it.
Defense Art is not overpowered? I've always seen Mass Fire as more OP, though I can see your frustration in the Expedition Russia level.
I don't recall getting stars for conquests. I also remember that there is a time limit, though I might have to search around the forum or do it myself.
They're called emblems, and the only other way to get them without going through the campaigns are purchasing them with money...Don't count on their helpfulness though, as they are only enough for you to get one tier 2 general.
Sorry if you're frustrated, though I do hope you come back to it again.