Opensips integration

I am running my fusionpbx installation in a virtual machine and it works nice for some time now.
I would like to integrate opensips in this virtual machine.
Coupple of questions that i have:
-No idea for the integration. Simply install opensips and its control panel in the same vm with fusionpbx?
-Do i have to create the same extensions to Opensips and Fusionpbx, or what?
-Where does the registration takes place? Do i have to change the ports from each machine?

I would appreciate some guidance for a simple config that would have:
-user creation
-voicemail
-DID routing
-IVR, voicemail routing
 
Opensips is hugely versatile with its routing script and loadable modules, but with this versatility comes complexity. From what you have written, it sounds like you are in for a monumental learning curve! There are hundreds of different ways that you could use Opensips, but you have not said what it is you are trying to achieve.