Custom Dashboard with a count of the number of documents and pages (within those documents) for a site and subsites

I am interested in setting up SharePoint so we can have sites broken out by department.  Within each department, there will be multiple sub-sites.  

What I'm looking for is a way to have each department log in to SharePoint and the first thing they see is a dashboard which shows: 

1. the number of sub-sites under the main department site,
2. the total number of documents stored in the department's site and all sub-sites below it,
3. the total number of pages within those documents (this would include PDFs, Word, Excel files, etc.)
4. the total number of employees who have access to the departmental site

Thanks in advance for any help.