Deduplication Pool Configuration ?

Hello,

Question 1:

what is the best practice to organize a Deduplication Pool in Backup Exec 2012 ?
A Disk Pool configured with Raid 5 or Raid 6 ?

Question 2:

What Size of Deduplication Pool is best Practice for a specific Size of Backup Data ?
There is a specific formel to calculate the size ?
I know it depends on the kind of backuping data, but existing a "rule of thumb" or anything else to help to find the right size ?

thanks for your answers