I will put this short and if needed we can discuss further.
For the integrated audit, there is an assessment of 'how integrated' your management systems are. This will determine how much time can be cut off the audit.
In my org, we are at 100% integrated.
So for the audits, you will demonstrate that those portions of the QMS are indeed integrated. For your 2 specifics: The management would review all aspects of EMS, OHSAS and QMS and be able to speak to them in the audit. For internal audit, you would need to show that your internal audit program is "integrated" - examples: same db to log audits, same training program (except for the technical pieces), etc.
This is the worksheet that is used. So you can see, there is more than just mgt review and IA if you want to achieve 100%. But you can meeet some and get reductions in time.
If you want more info - ask away. We do 3-4 integrated audits with all 3 standards each year.
