Yes, staff users are included in all the reports that I know of - I checked the daily engaged users, page views, and new contributors reports just now. The only condition that is put on users in the reports is that they are ‘real’ users. This is used to exclude the system user from the reports.
Another exception to this is the reports that you find by clicking the “Moderators” link on the dashboard - these reports only include site moderators (users who are only admins are also excluded.)
You can use the Data Explorer plugin for this. Writing the queries will take some work, but if you get stuck on that, there are members of this community (myself included) who enjoy writing queries, so it’s likely you can get some help.
Possibly we could add an option to the dashboard reports to allow for filtering by group. I’m not sure if allowing groups to be excluded from the report would make more sense that allowing the report to be run against a specific list of groups. I can see how excluding staff from the reports could be useful for some scenarios though.