Hi,
I don't know which patch level your system is but usually when you do EHP6 upgrade using SUM tool.
Sum tool takes account of all the pre-requisite note required for the upgrade so you don't need to worry about the pre-requisite.
You just need to take in account just the space ,cpu and memory.
I don't know what security patch you are talking about but you can validate all the patches after you have done the upgrade or just go through the security note and see what is the final patch level that they are delivered and to what target patch level you have planned to go.
Thanks
Rishi Abrol