During installation, entering the "Configure Printer"
menu, I want to enter my printer, a HP DeskJet 600,
explicitly listed under "HP DeskJet/DeskJet Plus",
but only can choose resolution 300x300, although this
printer is capable of 600x600.
yes, but the original deskjet/deskjet plus isn't, hence
the limitation. Try using a different driver (which the
description says, no less), or editing
the config files manually.