Scores are energies, albeit in nonphysical units. Therefore, more negative is more physically plausible.
Try some of the docking publications for those extra terms.
Fnat appears to be “fraction of native contacts”
I_sc is “interface score” = interaction energy
Irms = interface RMSD
I find no reference to “fa_ hack” or “fa_hack” in the code.
interchain_contact is some sort of filter on whether or not the chains are in contact.