Hi there,
Your cron job appears to be running every hour. Ideally you want to run it more often than that (having a drive sit there at 60+°C for up to an hour would not be good.) If you want it to run every minute then check the "Times and dates selected below" option and leave all check boxes beneath it on All.
You're right in that RAID is not a backup but SnapRAID is more of a backup than traditional RAID. If you accidentally delete a file or mess it up for example, you can simply retrieve a backup of it from the array.
If I may be picky, if your server suffers a powersurge and your 3 drives inside it get fried then you've not got a backup either
But seriously, go with whatever strategy you feel comfortable with.
With my setup, all photos (and other non-replaceable files) are backed up on a 1TB USB drive which is stored elsewhere. Some stuff is also on the cloud too. Everything else relies on the RAID array for protection.
Ian.