Users should be able to select individual or multiple cells of RadPivotGrid.

Available in the 2016 R3 Release.
Please take a look at our help article for more information: 
http://docs.telerik.com/devtools/wpf/controls/radpivotgrid/features/selection

Similar to Excel - RadPivotGrid could have an area, where you can select some filter/group descriptions.

Implement functionality to show a break down of items that aggreagate to current cell.

Available in the 2017 R1 Release (2017.1.117).
For more reference you can check the following help article: http://docs.telerik.com/devtools/wpf/controls/radpivotgrid/features/localdatasourceprovider/drilldown

Currently it is only possible to either show all or hide all subtotals.

RadPivotGrid is loading all data from OLAP Cube. It should be able to use on demand (lazy loading) pattern, so when a group is expanded, a new query is sent and only required data is taken from the server.

Currently when you have null value in a cell, RadPivotGrid considers it as 0. This way when you apply some Aggregate Functions, like Average for example, the result may not be as expected. For example if you have the cells 10, null, 10 RadPivotGrid will show as total the value 6.67 (for Average function). You should be able to exclude null values, so the value 10 will be shown as average for the mentioned cells.

Available in the 2016 R2 release.

I would like RadPivotGrid to sort the dates defined in OLAP Cube as dates, for example:
-Week 1 -Week 2 -Week 12   Instead of the current sorting: -Week 1 -Week 12 -Week 2

add a textbox which allows users to find matching distinc values when using report filters. Very valuable if you are dealing with many distinct values. 

The DistinctValuesLimit property is available in our R1 2018 Release.

If you apply a number format to a Count value in the RadPivotGrid, then it is ignored. The reason given is that count is always an integer, so it shouldn't need formatting. However, I'd like to be able to apply group separators. It's much easier to read 100,000,000 than 100000000. 

Available in the 2017 R1 Release (2017.1.117).

Hour, minute, second.

Add support for Hours/Minutes/Seconds steps. Also, add a DayNumber option.