Ok here it goes:
Your Publisher is your master copy of the CUCM Database. Your phones should be registering to your subscriber. You make changes on the Publisher and it replicates to the Subscriber.
The Sub is Read-Only anyway, so no changes can be made at the Sub level. It is a copy of the Publisher database.. the Publisher DOES NOT hold all the call processing etc etc..
Soft-Keys and features can be managed via the phone template in the Admin page.
Calling Search Spaces (CSS) contain Route Partitions, Which Contain Route Lists, and then Route Patterns - it designates which gateway the phone will use when it dials and what it CAN dial.
Please see
https://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a0080094b53.shtml
