Any two or more municipalities or counties may join or cooperate with one another or with an unincorporated area in the exercise, either jointly or otherwise, of any or all of their powers for the financing, planning, undertaking, owning, constructing, operating, contracting, or disposing of any dwelling, shelter, halfway house, or other housing located within the boundaries of any one or more of said municipalities or counties. For such purpose any municipality or county may authorize any other so joining or cooperating with it to act on its behalf with respect to any or all of such powers. Any municipalities or counties joining or cooperating with one another may by resolution appoint from among the members of the governing bodies an executive committee with full power to act on behalf of such municipalities or counties with respect to all their powers. Furthermore, any municipality may join or cooperate with an unincorporated rural area in the exercise of such powers, above, with the permission and concurrence of the governing body of the county wherein the unincorporated area is located. For such purpose, any municipality or county may authorize any other so joining or cooperating with it to act on its behalf with respect to any or all of such powers.