wal logging

hi

I have to setup some backup policies for our postgres server.
I had a few queries regarding corruption of database.
what are the steps to be followed in postgres regarding logical corruption, instance failures, block corruption, log corruption?

I am using postgres 7.3.9
I was checking out WAL logging. I enabled WAL logging in postgres.conf
I found the logs in the pg_xlog directory but don't know how to recover it

thanks,
kailash