The dual dichro S has a integral power supply. The non-S version requires a separate power supply. The ebay listing was for a "S", not sure what your LNIB one is.
Unlike most colorheads, the Dual Dichro (both versions) can be used with the 23C condensers OR diffusion. The ebay listings did not show the diffusion assembly so it would be condenser only.
Small brackets are required to attach the colorhead to the enlarger head. I didn't see those in the ebay listing.
This manual, though not for the S version, should answer many of your questions.