I am under orders (pressure) not to put all my 'stuff' on my wife's new MacBook. How is data transferred selectively when we have a common Wi-Fi network? Want to use the same printer, with the iMac using an ethernet cable and MacBook using Wi-Fi. Also, want to use the same Address Book but if possible have a separate email address.
Have been swotting up on the different ways of doing this and think manually is the safest. I have a WD 'My Passport' external drive for backing up the iMac so could transfer selected files/documents/software from that. Anything to be careful about? I assume it wouldn't matter that the iMac documents etc have been produced with OS El Capitan and are going to OS Sierra?
I think you're sensible to use external storage, you can control exactly what gets transferred that way. I presume that you will set up a separate Apple ID/iCloud account for your wife so she can punch, or not, independently.
Documents shouldn't be a problem. Address Book presumably you want selective contents but you can otherwise do an archive of the whole lot (from Contacts) and then import to the new machine.
If your printer is a network printer or supports Air Print then you can both just use it. Otherwise, you may need to connect it to one machine (presumably your iMac with cable) and share it from there for the other machine.
If you use the same Apple ID on the new machine that you currently use on the iMac, then it's likely that various iCloud options will be on and you will transfer stuff you were not expecting. Make sure (as Tony suggests) your wife sets up her own Apple ID