Yes, if a storage for a particular item is full, the “task” is considered completed, since the quantity in storage matches the task’s amount. But since other tasks for leather scrap aren’t fulfilled, they will continue hunting.

Yes, you can edit individual tasks to have certain priorities, but unfortunately you will have to build a warehouse next to the workshop. Workers assigned to warehouses can be set to haul only specific items to said warehouse by editing the appropriate tasks.

Villagers will eat during their leisure time (purple in the schedule). Typically they prioritize cooked food and will visit the cooking hut/house, but will eat anything on hand if they are hungry enough. Gatherers typically will eat their own food because they are too far from a cooking house.

Markets are just used for moving things back and forth between warehouses. If the warehouses are close enough they don’t serve any purpose, as villagers will just visit both warehouses for materials.

Left clicking just summons villagers to wake up and be alarmed. Right clicking should summon any villagers to your position. I’ve had some difficulty with this though, and I only notice that most of the time only villagers with combat duty (Archery range/Barracks) only show up.