Postgres vs. Redhat DB

I have a couple of questions regarding postgres and what it can handle.
Situation: 
I am looking a implementing postgres as my main backend for a internal corp. website.  I will have huge amounts of data (up in the gig).  I would like to have 2 database servers.  One will be the master and one the slave.  I will also have two web servers and a development server that will be used for development and moving all data to the other servers.  I am planning to implement vrrp on the web server; either by router on daemon.
Questions:
1. Does postgres handle data grouping similar to Oracles blobs and/or clobs?
2. Does postgres support replication or some type of master/slave relation? If yes, where can I find docs on implementation.
3. What is the difference between PostgreSQL and RedHat's version?
Thank You,
RAY HUNTER
Automated Test Group
Firmware Engineer
 
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