Segment reporting, split by profit center; still need segment splitting?

HI experts,

With reference to the subject of this post, I would like to have better understanding on the followings:

Settings (1) IMG > Financial Accounting (New) > Financial Accounting Global Settings (New) > Ledgers > Ledger > Assign Scenarios and Customer Fields to Ledgers ... I have settings of <Profit Center Update and Cost Center Update>

VERSUS

Settings (2) IMG > Financial Accounting (New) > General Ledger Accounting (New) > Business Transactions > Document Splitting > Define Document Splitting Characteristics for General Ledger Accounting ... I have profit center to be split (updated)

My concern, is I want to have segmental reporting. In the SAP material, it says that segment derived from Profit Center.

My Question: With the above settings (1) and (2), do I still need to have additional settings for segment? For example:

Settings (2), do I need to set segment here?

How about settings (1), any need to have <segment update>?

In settings (2), help file says: "This determines what fields in a ledger are updated when it receives posting from other application components." Not quite sure what this statement mean.

Thanks and regards,

sbmel