Some RLS updates coming in 9.4 . Updatable security_barrier views, as well as updatable WITH CHECK OPTION views. Can be done now sorta, but is a PITA.

Generally speaking, encryption isn't the answer. Hard to search, hard to sort, hard to index.

RLS using views works well, but has some issues such as Covert Channels. See http://wiki.postgresql.org/wiki/Row-security .

Don't think it would be a problem regarding replication, as long as remote databases can't query as they please.