I'm will be running Data Guard replication between two sites. Main site is set to Read/Write replicating data to Fail-over site that's is set to Read Only.
If I shutdown main site:
1. will Fail-over site automatically become Read/Write after recognizing Main site is down?
2. If so, after Main site is up again will replication be reversed (Fail-over -> Main)?
The answer to your questions will depend upon your setup. Do you have data guard observer setup for fast start failover?
Check this out for additional options:
Switchover and Failover Operations ( 5.5 Fast-Start Failover )