PostgreSQL Master server act as a slave for 2nd DB on new server
After a lot more digging I now know a couple of things:


A PostgreSQL server can't be a master of one DB and a slave for a second DB. In order to have a master DB and a slave DB on the same physical hardware with PostgreSQL I need to run two separate PostgreSQL services/clusters.
Updates are actually more expensive than Inserts because Updates have to seek out the row first. Also always try to append your Insert(or use a clustered index if necessary). 


Thanks