Thank you for bringing these issues to our attention. We can confirm that these both are bugs so I logged them in our PITS:
where you can track their progress. I also updated your Telerik account as a small sign of appreciation for bringing this case to our attention.
As a workaround for the selection issue in the Backstage, you can delay the selection. Basically if you apply the selection a bit later - after the control is displayed and initialized, the selected item will be displayed as expected. You can use your code behind logic and decide where and when to define the selected item of the BackstageMenu
the Telerik team