Both have everything online. That said, our whole language arts curriculum is brand new and overwhelming so using that online is going to be confusing.
(if you go to her Clever login it will have links to both)
The science and social studies books are also online, but we rarely use those anyway.
Chromebooks should go back and forth but charger can be kept home as long as she's responsible enough to keep it charged.
Yes, we were told to get the kids used to online learning, specifically using the Chromebooks, Google Meet, and Google Classroom from day 1 just in case we have to close suddenly. Unless there is a sudden outbreak at a school that is found in a single day, I feel there will be at least a little notice before going all online.
I got my second graders logging in to Google Classroom today and using Seesaw. I have a lot of special ed kids so it's going to take a lot to get them "independent" on a chromebook.
My daughter started CMS today after passing through FBES. She loved it there. Our experience as parents depended on the year. Some were better than others.