(2) To assure that land acquired in an urban renewal project is used in accordance with the urban renewal plan, an urban renewal agency, upon the sale or lease of such land, shall obligate purchasers or lessees:
(a) To use the land for the purposes designated in the urban renewal plan.
(b) To begin the building of their improvements within a period of time which the urban renewal agency fixes as reasonable.
(3) Any obligations by the purchaser shall be covenants and conditions running with the land where the urban renewal agency so stipulates.
(4) Any contract for the transfer of any interest in land by the urban renewal agency may be recorded in the land records of the county in which the land is situated in the same manner as any other contract for the transfer of an interest in land is recorded. [1957 c.456 §12; 1965 c.571 §1; 1967 c.312 §1]