Streaming replication version between different minor versions
AFAIK it will work and documentation says, it should work.


  In general, log shipping between servers running different major
  PostgreSQL release levels is not possible. It is the policy of the
  PostgreSQL Global Development Group not to make changes to disk
  formats during minor release upgrades, so it is likely that running
  different minor release levels on primary and standby servers will
  work successfully. However, no formal support for that is offered and
  you are advised to keep primary and standby servers at the same
  release level as much as possible. When updating to a new minor
  release, the safest policy is to update the standby servers first — a
  new minor release is more likely to be able to read WAL files from a
  previous minor release than vice versa.


https://www.postgresql.org/docs/9.4/warm-standby.html

For upgrade process

If you installed PostgreSQL via yum, yum update postgresql* should work. If you need rpms here is the PostgreSQL download link;

http://download.postgresql.org/pub/repos/yum/9.4/redhat/