Hello Shkelzen
The standard practice is to have a sandbox created and get the system upgrade there first before you kick start the upgrade on the landscape.
By doing this you can save a lot a troubles.
If I were in your place I would create a sandbox and get the system refreshed with the latest production backup.
By doing this I can find out the potential issues on the production system during the upgrade.
If you don't want to test the upgrade on a sandbox then you can start with the development system.
You just need to get the stackfile created and the get the upgrade guide from here.
http://service.sap.com/guidefinder
The present system configuration should be sufficient for EHP5 upgrade.
Regards
RB