I have already seen you ask about upgrading to ACS 7.0, so you must surely know that the latest version of Enterprise is ACS 7.0. And assuming you are already an Enterprise customer (which you would need to be in order to try upgrading), then you can check in the Hyland Support Portal what specific service pack / hotfix release of ACS 7.0 is currently available to you.
1) No, such a direct upgrade is not supported, neither from Community 5.0 nor from Enterprise 5.0 directly to ACS Enterprise 7.0. You should first upgrade to Community 5.2, then the latest Enterprise 5.2, and from there you can go straight to 7.0
2) There likely is some ACS 7.0 hotfix already for Enterprise, so an 7.0.0.X should be available in the Hyland support portal
3) Google Search or Search in docs.alfresco.com should yield you this: https://docs.alfresco.com/content-services/latest/upgrade/