That's something that's easier to do if you're using Maven as a build tool. Yes, there's an obvious need to swap out for newer JSF jars. Faces-config and web.xml shouldn't require any changes.
The exact set of jar differences depends on the brand and version of your server. The latest JBoss and GlassFish servers have the JSF2 implementation jars built into the server. Tomcat doesn't have JSF implementation jars at all, so you'd need to include them in the WAR.
Customer surveys are for companies who didn't pay proper attention to begin with.