Using PgBarman for PostgreSQL 9.3 backup
You are looking for point in time recovery (for them awkward moments when you forget the where clause  "delete from customers")

Barman sounds like a good way to go.  Barman uses built in Postgres functionality but makes managing the base backups and WAL logs a lot easier (backup and WAL log cataloger, Point in time recovery manager, manage many servers from 1 location)

Your suggested strategy sounds fine, you can set the backup location in the barman conf to point at your NAS, you can then set the archive_command in postgresql.conf to rsync WAL's to your NAS as they are rotated. 

There is documentation on their website http://docs.pgbarman.org/#introduction