Can my Airport Express A1264 wirelessly attach to a new Netgear Orbi wifi?
Possibly, but remember that the AirPort Express was designed and engineered about 10 years before the Netgear Orbi products were introduced.
So, you won't really have a definitive answer unless and until......another Netgear Orbi user reports that they have programmed the AirPort Express for the same tasks that you ask about.....or.....you try things out on your own network to see if things will work the way that you want.
The Airport Express currently has a printer attached via USB that has worked great. I'd like to keep that ability.
The AirPort Express will need to be reset back to default settings and then set up again to "join" the Netgear Orbi network. You will lose the current printer settings in the process, and it may be an open question as to whether you can set up the Express again to work with the same printer over the network.
We can tell you how to try to set things up, but cannot guarantee that things will work the way that you want. Hopefully, another Netgear Orbi user will see your post and provide some answers.