I am considering latest version now i.e. 9.4 or 9.5 on Linux 6.
Is there any difference in setup from 9.1 to 9.5?
There is no difference in the setup. Streaming Replication in the version 9.5 is a lot better with a lot of bug fixes specific to streaming replication and with a few extra parameters compared to the version 9.1. Please refer to postgresql documentation.