How can the Report Manager interface be changed to view only from the gray bar right below the four tabs, view, properties, history and subscription?
It can't except va URL access direct to the ReportServer service where you have the options to specify which bars you want displayed.
Report Manager has no options or settings to control layout.
Edit:
Report Manager is another application that gives a GUI to manager reports. It simply uses the Report Server web service in the /ReportServer folder. You can not configure Report Manager layout at all.
URL Access does not use Report Manager: it goes directly to the web service. You can decide which tool bars you want when using URL Access.
If you want to link to a report without showing the top portion of the Report Manager window, you can use the following path.
http://MyServer/ReportServer?/MyFolder/MyReport
You can pass other parameters to set additional options such as show/hide toolbar, zoom, etc. See the following link for more info.
msdn.microsoft.com/en-us/library/ms152835.aspx