build a skeleton project using seam-gen, deploy the ear, and take a look at what jars are included :) it does change as we upgrade to new versions of libraries.... generally you need far fewer to deploy than build!
To answer your questions about specific JARs you listed...
ajax4jsf-1.1.1-SNAPSHOT.jar - DO WE NEED THIS TO USE AJAX4JSF? Required for Ajax4Jsf, along with oscache JAR. Also RichFaces need these, too
el-api.jar - WHAT ARE THOSE FOR?
el-ri.jar - WHAT ARE THOSE FOR? Both are part of JSF implementation (either RI or MyFaces) and are required.
itext-2.0.1.jar - DO WE NEED THIS FOR PDF FUNCTIONALITY? Yes
jsf-facelets.jar - NEEDED? Yes, if you use Facelets
jstl-1.1.0.jar - NEEDED? Might be, if you use JSPs with JSF. If you use Facelets, this JAR is not required
myfaces-api-1.1.4.jar - NEEDED?
myfaces-impl-1.1.4.jar - NEEDED? Yes, but only if you use MyFaces JSF implementation. Not needed if you use RI
richfaces-3.0.1-SNAPSHOT.jar - NEEDED FOR RICH FACES? Yes
Also, some other JARs you listed are only needed for specific environments/tasks, such as Portlet JAR or JCaptcha