Print directly from finder, change defaults

You cannot change printer presets without manually launching the printer dialog and switching to a preconfigured black & white preset that also does not perform duplex.

Someone would have to write a complicated swift or objective-c drag and drop application that manipulates your print settings programmatically with NSPrintInfo/NSPrintOperation and then sends the dropped PDF onto the designated printer with the desired preset. You could even suppress the print dialog appearance.

If this was not a b&w settings issue one could at least configure single-page output via the lpoptions for the command-line lp printing tool and put this in an Automator application where you could just drop your PDFs onto it.

You could enable the CUPS web interface and set the printer’s default options there. I don’t know if this applies to Finder printing, but it’s worth a try.

You can access CUPS via http://localhost:631 in Safari, but you need to enable the web interface first, which is done with

cupsctl WebInterface=yes

in Terminal. In macOS Big Sur and Monterey there is a weird new behaviour which forces you to unlock the System Preferences padlock first in order for CUPS being reachable for Safari. See more about that at https://discussions.apple.com/thread/252638638

Once you are in the web interface you select Administration / Manage Printers (select yours) / Set Default Options

You can see in the screenshot that my printer defaults to color + duplex here.

This won't really help with batch printing - I don't know how to change the default settings when printing from Finder - but a possible workaround, a slow workaround, is to open the printer proxy of the target printer, select the pdf, then the option key, and drag the pdf on to the proxy's window. That should present a print dialog where you can change the settings - or use "Last Used Settings". Not really answering your question, but I hope this helps.