A: There's no absolute answer to the question of whether to deploy System Center 2012 first or Windows Server 2012 first--it depends on the priorities of the organization and where the greatest value can be found. If your goal is to deploy and System Center 2012, you'll need to keep some considerations in mind.
System Center 2012 RTM can't run on Windows Server 2012 nor manage Windows Server 2012, which means if you deploy Windows Server 2012 before System Center 2012 SP1, you won't have an enterprise-ready way to manage it. For a few servers to test specific features that's not a big problem.
However when rolling out Windows Server 2012 in production on a large scale, you need a way to manage it. I therefore think of deploying System Center 2012 SP1 first, so it can then help roll out and manage Windows Server 2012.
Organizations can use the beta of System Center 2012 SP1 to start evaluating both System Center 2012 and Windows Server 2012. By the time evaluation and testing are near completion, the RTM for System Center 2012 SP1 should be available to complete final testing and deployment to production.