OAC and Hyperion Planning PBCS Integration question about RPD and about report

We have two Oracle Cloud Services: OAC and Hyperion PBCS

I was able to import PBCS application metadata in OAC rpd's Subject Area, and am able to create report in OAC.

All the measures (or formulas) are showing up in SCENARIO dimension in OAC report.

I can add simple formula in my OAC report, as 'Calculated Item' of SCENARIO dimension - for example: Actual - Plan

where Actual and Plan are members of SCENARIO dimension.

Now I have two questions:

(1). In Essbase-OAC integration, after we import Essbase cube metadata there is an option to right click on cube (in Physical Layer) and then select '