Hi Aurora , thank you very much for your post.
Aurora The carriers and warehouse are chosen according to the location of the customer (delivery address).
Yes, you can set individual inventories available per shipping zone (set up zones in WooCommerce).
Aurora If the customer lives in the United States -> The stock will be deducted from the warehouse in USA, and USA carriers will be offered
Yes, if you set up a zone covering the US, you can then add that zone to any stock within the shop.
Aurora If the customer lives in Europe -> The stock will be deducted from the European warehouse, and European carriers will be offered
same here.
You can check the functionality in our demo stores.
Hope this helps.
Pavel