1. What determines when a country will declare war on you? I've had them being Very Happy with me and trading and in one turn, they declare war in the next. What gives? You get zero feedback from the game on how other nations are viewing you. I feel that it's just a simple random number generator that pops out declarations of war for no rhyme or reason. There seems to be zero modifiers according to the power, size and wealth of your nation. I've had the tiniest poorest countries declare war on me, when anyone would know it would be suicide to do such a thing.
2. Once you are at war, they never give up! I can be crushing them, yet my success or failure in the war has zero impact on the relations. Sometimes I don't want to have to conquer an entire small nation as I have more pressing matter to turn to. I can smack them around all day, destroy army after army, cause untold detestation in their regions, yet when I approach with a peace treaty, they tell me to go to hell. In reality, any nation would gladly accept a peace treaty offered by an overwhelming foe and given the opportunity.