Designing for Regional (cross geography) Performance

Hi, 

We are planning a deployment for an Enterprise customer (on a single Azure Active Directory Domain) and are trying to work out how to optimise performance. 

I understand that the front end of PowerBI Service uses CDNs, caching, closest data center etc to optimise the user experience. Perfect :)

However, for the backend, I have a few questions:

1) Is this located in the same region as the data is stored?

2) Can we have multiple backends to serve different geographies (e.g. one in China, One in Europe and one in the US)?

3) If you leverage Office 365 multi-tenancy, do these tenants share one PowerBI Service instance, or is a PowerBI service instance created for each tenant (Geography)?

The above 3 points assume import mode. For direct query to Azure Analysis Services in different Azure regions, how would that be best optimised for global users (from PowerBI Service) - are there options or does one region need to be selected?

I have checked through the docs but cannot find any definitive guidance about the best way to go about serving multiple geographies efficiently and avoiding the typical challenges of data transfer and latency to optimise the user experience.

Thanks