MEMBERSHIP INTEREST AND STOCK PURCHASE AGREEMENT BETWEEN KEYSPAN CORPORATION, TRANSCANADA FACILITY USA, INC. AND KEYSPAN ENERGY CORPORATION (Solely for the purposes of Sections 2.1, 4.5, 5.1, 5.2, 5.3, 5.6, 7.1, 7.8, 7.13 and 7.17 and Article XI...