Hello Shawn,
For reporting, you can set the categories you want to separate the reporting out by in the Columns. By default, the included metrics will be Attempts/Requests, Impressions, Clicks, Revenue, CTR, and Conversions.
To see Geo stats and fill rates per app and ad units, in one column, select Country, in a second, select App, and in the third select Ad Unit with Attempts/Requests and Impressions checked. Because fill rate is not included, you will have to calculate the fill rate by using the formula Impressions/Requests.
Please also see out documentation on Reporting Categories and Metrics Descriptions here:
https://dev.twitter.com/mopub/ui/reporting-categories-and-metrics-descriptions
If you need any clarification, please let me know.
Edward
