about your questions:
3) You can use a front end for that. Something like Apache HTTP, create virtual hosts and proxy requests.
5) Sure, that's what portals are all about. You can even user a portlet hosted elsewhere through WSRP.
6) Didn't understand well.. But I believe you are talking about a front end solution, like HTTPD..
I believe you are same as for the features. Give it a try and see it if fits you.
thanks for the answer, regarding the point 6 I mean i I create contents inside the site can I refer to it using a 3rd level domain?
I understand using a front end solution (trhu apache http for instance) it is possible.
Ok next step I will play with GateIn