The Commonwealth, any State public body or private entity by written agreement approved by the governing body of the city or county, as the case may be, may designate a redevelopment authority as its agent within the authority's field of operation to perform any specified activity or to administer any specified program which the Commonwealth, such State public body or private entity is authorized by law to do: Provided, however, That any such activities or programs shall be in furtherance of the public purposes specified in the Urban Redevelopment Law of this Commonwealth. Such activities may include, without being limited to, redevelopment, renewal, rehabilitation, housing, conservation, urban beautification or comprehensive programs for the development of entire sections or neighborhoods. It is the purpose and intent of this section of the act to authorize the Commonwealth, any State public body or authority to do any and all things necessary or desirable to secure the financial aid or cooperation of the Federal government in any of their operations.