Hello
1 - This could most probably due to the fact that the SAP_BASIS level of the system is on 0011 why MOPZ is preventing you from selecting stack level 10. If that is not the case then I don't know.
2 - As far as I know the ESS and MSS are part of the SAP_HR packages. Also read this SAP note 1303362 - ESS/MSS and Enhancement Packages
3 - While generating a stack file in MOPZ there is an option called "Add HR packages" and also there is an option called HCM Components.
4 - MOPZ will take care of all the dependencies involved. So create a stack file with the target level and start the update using SUM
Regards
RB