Everything from Art of War 3 about Confederate buildings you can find in here. Within the notes of every building, you will find priority for upgrades. This upgrade priority is telling us what the most important about the said building is, and we should loosely follow this order. What is meant by the term “loosely” is: you should prioritize the order of upgrades as we stated, BUT not at all costs. For example, if your high priority upgrade is 24hour long, and low priority is 10 minutes… it is obvious you want to click on the one with 10min duration.
For every building, there will be a list of requirements tied to it. Note: these requirements are actually what you need DURING the game, so the option of building or upgrading said building is unlocked for that game.