To what extent is it permissible to continue dealing with a wife who refuses to adhere to the legal hijab, what are the stages the husband must follow in admonishing her, and is it permissible for him to impose the hijab on her and prevent her from working if she refuses?

It is your duty to teach your wife that the hijab is obligatory, and you should do so gently, explaining its conditions to her. If she refuses, you have the right to compel her to wear it.

As for preventing your wife from working, it is the husband's right, unless she stipulated before marriage that she would work. In that case, he must fulfill her condition if she adheres to Islamic manners, the most important of which is the hijab.