I cannot exactly understand some details of your question.
Are you referring to Lightstreamer 4 (Duomo) or to the forthcoming 5 (Colosseo)?
Moreover, are you really in a clustering scenario, or did you report Clustering.pdf only as an example?

In fact, the answers may differ in the various cases.
(According to the reported paragraph of Clustering.pdf, you seem to be interested in an answer for Colosseo, which is actually more complex than the Duomo case).

Only the second question has a common answer:
Lightstreamer does not pose constraints on the number of different hostnames that you can use to address a single running instance of the Server.