HR Support Packs for EHP4

Our ECC 6.0 EHP4 system is at SPS7. We need to put in the year end HR patches which would talke it from hr patch 27 to 40 (yet to be released). I have a couple questions

do we have to go to SPS09. That might require much more extensive testing then if we do just the HR packages. If we do only the HR packages, it also calculates some other packages are needed at patch 8 level for sap_aba, sap_basis, sap_bw, and a few others. Those would have to go in per spam.

We have ess/mss in a nw701 portal, and it looks like from the release notes if you go to EHP sps09, you have to upgrade ess/mss java compontes to a 7.3 portal. How can we tell if a ess/mss business package needs to be upgraded in the above scenario.

Would any other connected systems need patching such as mdm, BI abap 7.01sps5. CRM, SRM

You don't need to answer these, but I am having a hard time finding notes that say what needs to be updated in other environments if you do EHP4 support packs. Do you have any links?

Thanks, Pat