You could start with some of the product documentation available on support.mcafee.com, look up KB76064 and start with the quick tour & best practices guide for your build.
The box is already running & its in production.
And the best part is no one knows about it, And i just want to familiar on this before getting into it
At first, there is no problem with Upgrade when it is in Production. NSM ca be upgraded any time you want and it will not do effect on sensors during upgrade process.
Check the link below and enjoy the videos:
In Additional, If you want to do some change or Upgrade, ensure that you have a right guide in your hand.
For Documents just refer to the kc.mcafee.com and search the material you are looking for.