I'm taking care of a few hosted servers + VPS, some of them with Plesk. I'm rather very experienced with DNS problems; be mindful that the related problems more often then not imply various interactions with various authorities, so it might be that part of the action goes into setting things straight in other parts then on the server itself. Migrating e-mails with minimum to no disruption is the most challenging task, but that also depends on how many users and how many e-mails / time unit are going through the system...
Why is there Centos 6.0 on the server... ? There are know security issues with it, and the up-to-date CentOS is 6.3.
Overall, it might take a few days to have everything working as wanted and looking for a minimum of disruption.