I don't really know anyone that works nightshift as a dba. They are oncall for emergencies, but its not shift work.
Once you move into an organisation and you find which problems cause most of the overnight emergencies, then you can usually clear it up with some automation scripts and being proactive in monitoring the servers.
I have no experience with freelance jobs, but I've looked at a couple of web based sites where jobs are posted.. good luck, there are usually 10+ people with very good feedback ratings offering to do the work for very low pay.
If you were working with SQL2008, there is very little difference in terms of DBA support for 2012. Just read through the whats new page on books online for 2008R2 and 2012 and maybe have a look around at a few SQL blogs, go back and attempt the QotD from here and read through the discussions.