The accounting book in the mansion is used to stock building supplies, create trade able items and then trade.
I'll preface this with the more "homestead missions" you do to get more people in the homestead map will give you more and more items to stockpile and create - thus giving you more and more items to trade.
Used to gather raw materials such as lumber, iron ore, food, plants and farm life. If you've been in the frontier hunting, stocking up on food/hunting items is pointless, as the bottom option "Connor" will have a ton of venison and pelts.
Perhaps the most irritating part. This is where you use the items above and craft things like barrels, ales and furniture. The easiest thing to do, at least early on, is stock up, and then go through each category in crafting, and see what you can actually make. Early on, barrels, and a few other items will be about it. You'll see you have the person needed, and the raw materials so you can craft the items. As you get deeper into the game, more things will be open, and in turn, you'll need to craft items, and then mix it with other crafted items. For example, to make ale, you'll craft a barrel out of the oak lumber, and then use the barrel mixed with the barley stock item to make ale.
What makes it a pain in the ass, is that it resets your position in the crafting recipes each time. So, if I'm down on "metal works" and I craft rings, and then I want to craft something else, it resets me to the top of the crafting recipes and I have to try and find my place. No tutorial in this area was a huge pain in the ass, and took me quite some time to figure out.
Exactly as it sounds. You craft items above, select a convoy slot, and then select which trader will give you the most money for the convoy.
I'm about done with the story for the game. I think I'm at like 80% done. Some awesome battle missions.