We are new to Chegg. Need info on how etextbooks work. Specifically......if we rent a...

We are new to Chegg. Need info on how etextbooks work. Specifically......if we rent a Chegg etextbook does the book download to the student's computer? If so, what happens if the computer later on has issues and won't start up? Or are the ebooks in the "cloud" when they are used by the student and can they be accessed by the student on a new or different computer? Can the textbooks be used offline, or does there need to be internet or wifi for them to use the books? Can the book be downloaded or copied to an external hard drive to be taken to a different computer away from the original computer (such as taking the book on an external drive to a computer lab on campus)? Sorry to ask these questions, but we are in the Midwest where we have had severe wind storms and have been without internet for days and we are wondering whether using etextbooks is such a good option for our student.