The characteristics of the extended Hubbard model with the pair–hopping interaction J, i.e. the Penson–Kolb–Hubbard model, are analysed for the case of attractive J (J > 0). The effects of on–site U interaction on the properties of the s–wave superconducting state and mutual stability of the superconducting s–wave and magnetic orderings are examined. The electromagnetic and thermodynamic characteristics of the s–wave superconducting phase for arbitrary particle concentration n and interactions are analysed. The system is evaluated for the case of nearest–neighbours hopping on d–dimensional hypercubic d = 2 (SQ) and d = 3 (SC) nonfrustrated lattices. For SQ lattice the effects of phase fluctuations on the properties of the superconducting state are discussed within the Kosterlitz–Thouless (KT) scenario. The KT critical temperatures TKT are calculated and compared to the Tc obtained within the BCS–HFA. The Uemura type plots, TKT vs. λ2(0), are obtained and evaluated as a function of pairing strength and concentration. The results are compared with the case of repulsive J (J < 0) pair–hopping interaction.