There is an official RT extension for doing "standard responses." It's called RTFM. (RT Faq Manager) http://bestpractical.com/rtfm/. Our customer support loves it.

RT Rocks. Great software, great community, lots of good extensions available. Our company is a heavy user of RT. We have one instance for external requests and one for internal requests. It was really easy to customize for our exact needs. Note: I wrote Asset Tracker, an asset tracking (duh) extension to RT. http://code.google.com/p/asset-tracker-4rt/