Congrats on the new purchase; I like the blaze red.
I know you will enjoy the Xfire as most owners on the forum do.
There have been some problems that you will read about but over-all the experience has been great.

As far as the VIN on the signature, there is no particular reason for that. I don't have my VIN there.
It's your option. As you know VIN is unique to your car and I guess is part of your vehicles signature if there is such a thing.