Yes, our extension allows updating & retrieving stock data using Magento SOAP API v1, v2 and Magento REST API.
Follow the link below to see the settings.

According to extension logic two orders should be placed.
Follow the link below to get more information.

If a simple product does not have weight, Magento converts it into a virtual product and such products cannot be assigned to Warehouse. Follow the link below to see the settings.

No, it's not possible to bind a warehouse to the certain way of shipping, but there is a workaround we can offer. Read the full answer to learn the details.

The Warehouse extension does not have such settings, but the required result can be achieved with the help of Customizable Options for a product. Read the full answer to see the settings.

Unfortunately, no. There is no possibility to import stock data automatically. Read the full answer to get more information. 

The products will have the corresponding status, depending on their settings per Store View. If a product has qty 0 in one Warehouse the stock will be changed to out-of-stock automatically on the front-end of the assigned store view. To get more information, please read the full answer.