Me and you had the same basic Idea about war declarations by alliances. One think I would like to add to your list of things a war declaration does is have both alliances embargo each other. The would give the embargo feature some much needed power and also fits in with how an actual war works. I also think that nations should be able to try and defy the embargo but at the risk of it not going through and the resources/money are lost or the alliance to have an in game way of seeing it and a way to punish them.
