We discuss some aspects of the SU(3)C×SU(2)L×SU(2)N×U(1)y×U(1)y′ models originating from Calabi-Yau compactification of the E8×E′8 heterotic superstring in ten dimensions, with subsequent gauge symmetry breaking via Wilson loops in the nonsimply connected Calabi-Yau manifold. RGE for the standard model gauge couplings are analysed including two-loop effects. Problems with lepton number violation due to the symmetry can be solved by having a discrete symmetry acting on the standard model singlet SU(2)N doublets of the theory together with soft SUSY breaking terms and a radiative gauge symmetry breaking scheme. Gauge singlet superfields may play an important role in fully breaking the group down to the standard model by radiative corrections. The charged lepton mass matrix can have a natural mass hierarchy between first and higher generations (with radiative mass for the electron). An alternative scheme involving more than one pair of Higgs doublets to give first generation masses is discussed.