Hi Doug,
When you plan to upgrade to EHP6, you need to first check whether your system is ready for EHP6 upgrade. Whether your database and OS is compatible for upgrade.
When you start the upgrade to EHP6 you may use solution manager for generating the stack file which will take care of all the pre-requisite patches from EHP1 - EHP5 as well as compatible kernel.
Hope this helps.
Regards,
Deepak Kori
