Vertical grip and shutter release cable are great accessories and are critical to me, so
even though you seem already convinced. Haven't used the Canon models, so I'll keep quiet and let others pipe in.
Skip loading images from your camera directly to your computer. Pick up a $10 12in1 card reader and save yourself time and camera batteries. No name brands have worked fine for me and friends (they all use the same chipsets).
Yup, drives will fail and you're right to be thinking about this now. Personally, cards get dumped into my laptop, sorted, then dumped onto a
NAS 4 drive RAID device. The NAS has had drive failures and when it does, it sends me an email and text page as to which drive has issues, then powers itself down. I've survived several drive failures successfully this way. This is however overkill for most. I just make the most out of my geekyness.
I also periodically backup my images folder on the NAS to an external hard drive via
robocopy mirror option which is very fast. The external hard drive then gets locked up into my safe. Other options for off site storage is a safe deposit box or simply a locked drawer in your office at work or even a buddy's house. I shoot primarily RAW photos, so online options are not able to support me at a reasonable price (I'm currently at ~180GB).
Another great option you mentioned is to archive off site using DVD media. However, I've actually had media fail on me before, so you may want to consider some of the gold DVD media which has much better guarantees on longevity. (
Delkin,
Kodak, and
Memorex)
In a nutshell, as
jwardell said, have at least two good places where your images are stored and you'll be set.
Enjoy your new camera and please show us your photos.
