Upgrading 2003 doamin to 2012

Hello,
I am planing to upgrade our domain to 2012 server and have a few questions.
We currently have two domain controller ruining 2003 standard. I am adding two physical servers and will be using Hyper-v.  
1. One major concern that I have is that we having some group policies that is linked to the default domain  GPO . There are way too many settings configured on this policy and I was wondering if I could somehow reset this before running the upgrade. Or wanted to know if these polices would come over in the 2012 domain controllers. I will eventually get rid of the 2003 domain controllers. I don't need any of the configurations in the defualt domain policy to come over and I like to reset all to defaults.

Also, I was wondering about the anything that I should watch for or any step by step instructions for doing the upgrade.