1) That just seems kind of a cludgey way of insuring data integrity that the software should already be taking care of. After doing some more reading I feel pretty confident I'm ok running just Synthetics based on a few peoples' experiences and also the fact I have the option "Verify Synthetic Full" enabled. Here's a quote from the v9 BoL:
"Use the Verify Synthetic Full advanced backup option to ensure that never-changing files are backed up. This is especially useful when synthetic full backups are used consistently to replace conventional full backups."
Also, as I was typing this my Commvault account rep emailed me and told me his SME stated the Synthetic Fulls are fine to use exclusively. Issues with pruned/corrupted data was related primarily to older versions using tape.
2) Unfortunately, I definitely have to verify the tape jobs since those are my last line of defense in the event there's a fire/etc that takes out the building. Currently though my estimations on my windows for jobs such as verification, aux copies, etc are such that I can afford to verify everything. I was just curious if it was necessary from the maglib side since that data is essentially being verified when it's aux copied.
3) Here is the link to the discussion in question:
Just my 1.4 cents (after taxes)