Additional SQL Server features and topics not covered by specific categories
First of all, this is a technical forum, and your questions are of a legal nature for which you cannot get an authoritative answer here. You need to contact your local Microsoft representative for an answer that is binding and which will take you through a license review.
But so much I know about the licensing that for the scenario you describe, both servers needs to be licensed, no matter if they are two physical servers or two VMs on the same physical host. For the third question, I am less certain, but my gut feeling is that you can't do this. You need a license for both servers. But it might be possible buy a license for less cores for the machine running PBIRS. For the last question, I will need to pass.
If you have not done so, please study the SQL Server Licensing Guide.