Sorry these are more "legal" contract type questions which I cannot answer in an online forum. You will have to ask an attorney about the NDA which is a form of legal contract.
Regarding the patent and licensing question, usually if you only have a patent in the US you are only protected in the US market. In theory I guess you could get a company to agree via a contract to not make or sell in other counties or compete with you but again that would have to be worked out with your attorney handling your NDA and legal contracts.