(k) To enter, with the approval of the mayor or board of selectmen and the department, into agreements with the federal government relative to the acceptance or borrowing of funds for any project it is authorized to undertake and containing such covenants, terms and conditions as the operating agency, with like approval, may deem desirable; provided, however, that nothing herein shall be construed to require approval by the mayor or selectmen or the department of requisition agreements and similar contracts between an agency and the federal government which are entered into pursuant to an agreement approved by them;
(l) To enter into, execute and carry out contracts and all other instruments necessary or convenient to the exercise of the powers granted in this chapter;
(m) To make, and from time to time amend or repeal, subject to the approval of the department, by-laws, rules and regulations, not inconsistent with pertinent rules and regulations of the department to govern its proceedings and effectuate the purposes of this chapter;
(n) To join or cooperate with 1 or more other operating agencies in the exercise, either jointly or otherwise, of any of their powers for the purpose of financing, including the issuance of bonds, notes or other obligations and the giving of security therefor, planning, undertaking, owning, constructing, operating or contracting with respect to any project or projects authorized by this chapter located within the area within which 1 or more of such authorities are authorized to exercise their powers; and for such purpose to prescribe and authorize, by resolution, any operating agency so joining and cooperating with it to act in its behalf in the exercise of any of such powers;