Hi Niyati,
Regarding SPAU activity, as far as my understanding the system will automatically list the respective components which are eligible for change. So, we need to make the changes in the listed component.
Regarding the activation of the business functions, you need to talk to the solution architect as this is a very important step involving multiple teams and Solution Managers. Also, can you check EhP3 documentation that mentions prerequisites of Activation of any Business Functions.
I will also continue to check from my end an will update you.
Hope this helps.
Thanks,
Samantak Chatterjee.