Review in Book mode

To be more clear :

I have seen that we can select a part of the page (by example a text frame) and assign this text frame to one people in order it can review it inside InCopy.

But now, how to select all the book (made in indesign) and assign all this book to one people in order to be reviewed inside InCopy ?

In InDesign, how to assign the whole Book for a review in InCopy ?

But if my reviewers don't use anymore Microsoft Word, and choose to use only InCopy, is it a good solution ?

My reviewers don't have Indesign. 

My goal would be that they can modify the text themselves, and that it could be updated aitomatically in my file. So you think the best is to use InCopy workflow ? But I need a very simple way to do it for my reviewers : is it difficult to learn InCopy ?

Actually my reviewers work on Word. Is it a better way to give up Word and choose InCopy for them ?

There are many ways to do it

• modern share for review https://youtu.be/II8skrBAXXQ
• PDF as James says already (if you have many correctors you can use acrobat.com to collect review things or you can send this PDF to a few people and collect their comments - https://www.adobe.com/acrobat/hub/how-to/merge-comments-from-two-pdf-files.html ). And you can import this comments to your InDesign - https://helpx.adobe.com/indesign/using/import-pdf-comments.html 
• InCopy workflow (I do prefer this, but needs to have some skills and nervous for bring somebody to understand and using new soft).  And you really don't need to give whole the book. Give it something one-by-one to your corrector. https://helpx.adobe.com/incopy/using/basic-managed-file-workflow.html
  Main plus here - you won't add/correct/delete/etc words when your corrector will do this by his hands. No monkey business with PDF to see, to understand what corrector write and add this into publication, because corrector do this directly inside InDesign file through InCopy.
• old-fashioned workflow with real printing on the paper
• publish online feature
• nomen illis legio

And only you can decide which of these methods is closely to your destination. 

From the Book menu, export all the chapters to PDF. That's the most universal format, and can be locked against things like printing and copying if needed.