A:AnswerNo, the Brother MFCL2717DW is not able to add an extra tray. I apologize for any inconvenience this issue may have caused you. Below is a link with the Brother MFCL2717DW specifications.
Answer Link: https://support.brother.com/g/b/spec.aspx?c=us&lang=en&prod=mfcl2717dw_us
A:AnswerI'm not sure about AirPrint, but if the printer is connected to the same network as your apple devices, they should be able to find it to print to just fine.
A:AnswerThe Brother MFCL2717DW does not support making auto duplex copies using the ADF. A similar model that does support this feature is the MFCL2750DW.
A:AnswerThe printer function certainly works with Chromebooks, I'm unsure about how to scan with one though. Chromebooks use a generic driver for communication with all printers they are connected to.