with firewalls/ abutments allowed on two (2) side property lines only or on one (1) side property line and the rear property line and absolutely no firewall/abutment at front property lines for R-3 and R-5 uses; and with firewalls/ abutments allowed on two (2) side property lines only and absolutely no firewall/abutment at the front and rear property lines for R-4 use.