Yes, you can specify whether to print to USB or Ethernet printers, so you can have one of each, even though they're the same physical device.
Yes, but am I allowed to have both the USB and the Ethernet cable connected to the printer? What happens if I am printing something through the Ethernet connection and someone sends a USB print job in the middle of it? Does the print queue take care of conflicts?
And transferring data is easy and quite automated using Migration Assistant
But automating is NOT what I want to do. I would guess that 80-90% of all the data she has in her computer is junk that I don't want in the new computer. So I am afraid this means hours of work. For example, her email account has more than 11,000 unread emails in the in-basket. I tell her "Please, just delete everything more than 60 days old" but no, "some of it might be important". Sigh...
tanstaafl.