by fizzmore
Well again....buying requires spending money and doesn't take an action. Building requires an action and uses building resources (wood, clay, iron, brick, steel), not money. They've very different requirements, and so which you do will depend on what you have available.Food is anything with the food icon (fish, smoked fish, bread, and meat). Francs can also be used as food.
I'd highly recommend rereading the rules and checking out some of the videos here for getting your head around such core concepts.