  We extend previous work on the minimal D-term inflation model modified by
Right-Handed (RH) sneutrino fields to include additional inflaton-sector SUGRA
corrections and two-field inflation effects. We show that SUGRA corrections
simultaneously allow n_{s} to be within 3-year WMAP limits and the cosmic
string contribution to the CMB power spectrum to be less than 5%. For gauge
coupling g < 1, the CMB contribution from cosmic strings is predicted to be at
least 1% while the spectral index is predicted to be less than 0.968 for a CMB
string contribution less than 5%. Treating the inflaton-RH sneutrino system as
a two-field inflation model, we show that the time-dependence of the RH
sneutrino field strongly modifies the single-field results for values of RH
sneutrino mass m_{\Phi} > 0.1 H. The running spectral index is \alpha = -0.0002
when m_{\Phi} < 0.1 H but increases to positive values as m_{\Phi}/H increases,
with \alpha > 0.008 for m_{\Phi} > 1.0 H.
