Q1. Looks easy, but this requires long workaround.
However, if you are ok with this view, it's easy eough.
Change the value of average to discrete and put it next to dimension.
It's also difficult to put this column to right side unfortunately.
This also depends on your final dashboard requirement.
I mean if you want to set date filter as universal across worksheet, below solution does not work.
As long as you filter one worksheet by date to show 6 month 12 months difference, this table calculation works.
Here is a technical background.
If you still want to keep last three months avg, that field needs to be revised based on new table calc setting.
data dashboard_SM_10.0.twbx 599.7 KB