Setting content expiration on IIS 7

See also Mike Knowles post on SharePoint IIS Content Expiration settings.
On IIS Manager, click on the site under the "Sites" folder.
Expand to show the subfolders under the site.
Click to select the subfolder you want to modify.
Go to Features view on the main panel.
Open the "HTTP Response Headers" feature.
Under "Actions" on the right column, click on "Set Common Headers..."
You should see the content expiration settings in the popup ("Set Common HTTP Response Headers") that appears.

Error: "Could not load file or assembly ... or one of its dependencies. The system cannot find the file specified."

Created a class with common functions and included it in a SharePoint solution.  Deployed successfully.  But when browsing a page on the site it gets the "could not load file or assembly..." error.  The class dll isn't getting in the GAC.  Got the solution from this stackoverflow thread:
Add an Assembly element for the missing dll into the manifest.xml by double-clicking on Package.package on Visual Studio, going to the "Advanced" tab, and adding the assembly.

Site columns deployment error

Was getting this VS deployment error on a SharePoint 2010 solution:
"Error occurred in deployment step 'Activate Features': The field with Id {guid1} defined in feature {guid2} was found in the current site collection or in a subsite."

Found that workaround #1 from this article worked for me.