Yes she can use an email address. She does not need a phone for FaceTime. It works over WiFi or cellular. If she has WiFi at home and doesn’t need to have her iPad with her when she is out of the house (during nonpandemic times that is), then a WiFi iPad will work just fine. I take my WiFi only iPad many places and am able to use it because so many places offer free WiFi.
Depending on what else she plans on doing with it, my next suggestion would be to buy the iPad with the largest amount of storage that you can afford. You cannot add physical storage to the device like you can on a computer. I bought my son and daughter the iPad Air 4 for Christmas and the screen size is close to 11” which I think works very well for a tablet. The iPad Pros are larger, but they are overkill for what they need.
You can compare the various models for yourself here.
https://www.apple.com/ipad/compare/