Epson XP-340 looks like it doesn't have a paper-handling capability to do double-siding in one pass so the best you could do is print all the odd pages and then put those pages back in the input tray and print all the even pages (in reverse order?). Sometimes the printer driver presents this as a choosable option but if it doesn't then you can tell Word to do this with two separate print commands.

Greyscale is another option that 'should' be available to you as the printer specs give a different speed for black and white vs colour printing. Are you sure there is not black and white print option?

I would go onto the Epson website and download the latest print drivers to suit your device on a Mac. The disk that came with the printer may not be the latest available driver.

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Andrew Lockton
Chrysalis Design, Melbourne Australia