As for the option to compare different time periods in freeform tables, that feature is available to everyone. Maybe just make sure that you are right-clicking in the right spot. You should be right-clicking on the metric itself, at the top of a column, and then you can choose to add a comparative time period.
To "how can I exclude 'unspecified' data in the mobile scorecard?"
Look to the right pane where you will see your dimension(s) listed for the tile or detail slide you have selected. Click the chevron to the right of the dimension. Hover over "unspecified" until you see the icon to exclude it and then click it.