Power KPI Matrix 3.1.1

Hi Bi developers, 

I require assistance with creating a 3 diemensional daily target visual on Power Matrix 3.1.1 and require some assistance please. 

1) My targets and actuals are on seperate report servers, is it possible to simply define relationships join on fields in PowerBi. Thus the visuals work with slicers ? 

2) What is the difference between the index and indicator ? 

3) Can the category be used for channel segment or different products as a grouping ? 

I have more questions but I feel these are my most pressing. 

Thanks