Are the expressions "If I ever marry, I will wear the hijab" and "If I ever remove my hijab, may God blind me and cut off my legs" considered vows that must be fulfilled, and what am I required to do concerning this?

The hijab is an obligation upon women before and after marriage. A vow to perform an obligatory act is not binding, and no expiation is required for abandoning it. It is not permissible to supplicate against oneself, for the Prophet, peace and blessings be upon him, said: "Do not supplicate against yourselves, nor against your children, nor against your wealth. For you might coincide with a moment from God in which He is asked for a grant, and He responds to you."