The reports were one of the major strengths of FrontPage and a good thing that Microsoft maintained them in Expression Web. This is one of area that excels past every other web development tool that I've used, including Dreamweaver.
From these reports you can mange your entire site and the capabilities exist to attach style sheets and DWTs to many pages at once! To access this summary of reports just click the tab Web Site tab at the top of the editing view, and then click on reports at the bottom of the editing view. This will provide a hyperlink summary of the reports.
I've clicked the Style Sheet Links and up comes a detailed report.

Then select the pages you want to apply a style sheet to, right click and select Mange Style Sheet Links... The dialog box shown above pops up. Click Add and another dialog box opens that allows to you select the applicable style sheet, click OK and you've just applied the selected style sheet to all of the selected pages. Cool!
Let's take a quick look at all the toolbars of Expression Web.