Please discuss what are and why use portlets
Why would I want to use java portlets above tomcat and gwt?

These technologies are not directly comparable. Coming from regular web page development, Portlets seem like a very restrictive technology. But then the value of Portal servers is largely the control they give to administrators and users - the fact that this makes your life more difficult is irrelevant.

Would portlets make it less- or un- necessary for me to use jsp and jsf?

You can write directly to the output, just like you would in a Servlet. You probably still want a view technology (that will have to support portlets).
Why would I want to use java portlets above tomcat and gwt?
Would portlets make it less- or un- necessary for me to use jsp and jsf?
Has Jboss been part of the portlet evolution culture? Does Jboss satisfy the portlet jsrs?
What portlet implementation/brand would run on gae java and gae python?
Are portlet specs due to peer pressure from php cms culture?
What are the equivalent of portlet and portlet jsr in .net?