You can still do clustering and all the other tricks with the free version, right?
Yes you can. I am trying to find a free way to proxy. Also if running in domain mode do I need apache to proxy
Domain mode & clustering don't have much in common, one is way of managment many server other is for high-avalibilty of applications...
read more about managment operating modes:
As goes for mod_cluster, it is free, you can download it and use it http://www.jboss.org/mod_cluster
also you can use mod_proxy_ajp or mod_jk to work with AS7 without any problems.
also you can use any other proxying solutions out there (nginx, varnish, iis, lighttpd...), jboss functions as web server and you can proxy to it as you could to any web server.
and just for info, all stuff that is present in EAP is also avalibale in community, but you might need bit more work to put it all together.