SAP Release Recommendation:
In general SAP recommends that you use the highest version of SAP PI / SAP PO. SAP PI / SAP PO is shipped within SAP NetWeaver, the current release is 7.5. Any other SAP NetWeaver releases below 7.5 are out of maintenance .
If you are a PI Dual Stack customer who plans to upgrade to a higher release, the information available in the note 1515223 - SAP Process Integration and SAP Process Orchestration: Release Recommendation, should help you to come to a decision on
whether you go for a PI Dual Usage Type (from 7.5 on) or migrate to SAP Process Orchestration.
For further information see the blog post SAP Process Orchestration – What options do I have when upgrading or migrating to release 7.5?
For information on new functionality delivered in PI/PO Support Packages for 7.50 see What's New in SAP NetWeaver 7.5 (Release Notes
Applying a Support Package Stack (SPS) or Patch:
For further information on the differences between a Support Package Stack and a patch see the information in the KBA 1746599 - The difference between a Support Pack and Patch in SAP PI.
How to check the Patch Levels (PL) of the individual PI Software Components in your PI/PO system is documented in the SAP note 1381878 How/where to check the patch levels of your XI/PI system.
It is important to remember that there are dependencies between some individual PI/PO software components, the dependencies are described in the KBA 1335523 - FAQ: Deployment PI, PO and AEX Patches.
To ensure that you have the latest patches applied for your PI/PO software components please follow the steps in the KBA 2282200 - How to select latest Patch Levels when updating PI Support Packs or Software Components.
How do I find the right SAP PI/PO guide to : Install a new System, do a System Copy or Migration or when Upgrading and Patching?
There are no official SAP Guides for PI/PO activities like Installing a new System, executing a System Copy or Migration or Upgrading and Patching a system. For PI/PO the steps for these activities are described in the SAP NetWeaver Guides.
You need to download the relevant SAP NetWeaver Guide and then locate the PI/PO specific section in the guide. To find the correct guide to use you can use the steps in the KBA 2574603 - PI: Official SAP Guide Finder
Important: If there are pre or post activates that you need to execute on the PI/PO system there will also be described in the relevant section of the SAP NetWeaver Guide that you follow.
In most cases it is mandatory to execute a configuration wizard. For detailed information on which CTC Configuration Tasks (Wizards) to execute in PI/PO systems and when to execute them please see the WIKI post Which CTC Configuration Tasks (Wizards) do I need to execute in my PI/PO systems and when do I execute them?
System Health Check:
After installing or patching the system you can check that the essential functions of the PI/PO system are work correctly by doing the tests described in the pdf document attached to the note 817920 - XI/PI/AEX Readiness Check 3.0/7.0, 7.1, 7.3, 7.31, 7.4, 7.5.