Details and Steps to integrate WOPI with office 365

Question

Currently, we having the application that has office files stored in cloud storage.

So, we would like to provide online edit for office file and also collaborative edit feature to our users using WOPI integrate with office 365 for the web.

We need to know the following requirement details for WOPI integration,

1. Steps and requirement details to apply for 365 cloud storage partner programm (CSPP).
2. Need to know the license type which we need to use for the Microsoft 365.
3. Does all users in a tenant need to have Microsoft account or license? or Is it possible to use one license and add users under that single license? Kindly share the cost for this integration in detail.
4. Share the Estimated total time to apply CSPP and complete it upto commercial environment in detail.
5. Share the Online Office (WEB) version details such as (Microsoft Word, Excel and PowerPoint) used in this WOPI integration.
6. Does this WOPI integration have any expiration date? kindly share the expiration details