The doubt is:
"how can we deploy a JSF project that communicates with the EJB3 that exists on another tier". Or in other way, making a separate deployment for EJB3 and another deployment for JSF, is that possible? Is there any configuration changes needed?
For most apps Seam makes tiered development unnecessary (in our opinion at least), so you aren't going to find many examples of it. But you can still do it. Just declare your EJBs as normal, and inject them using @EJB into your Seam (EJB) components as needed (or use whatever method you like to get hold of the EJBs). It's tricker to get the SMPC working here, but you can. You should be able to declare multiple ejb modules in your application.xml if you want to package your ejbs seperate from your seam components
I believe that ajax4jsf offers this ootb - take a look at the ajax4jsf docs and the booking example.
The reason for the dissociation (in three tiers) is that we are gone be evaluated separated. Is like two projects that connect each other.
You may say "ok, use jsf backing beans", but seam rulez :) (XML hand-writing not)
I'm gonna see what @EJB brings and so on.
For the second doubt:
I definitely need to read the docs and search more for the subject.