what structure do you mean?
Organisation structure?if yes it is called Org. Plan

You can replicate Purch Org,purch group,material 
master,vendor master from backend.
you can create PO in SRM and replicate Po in the R/3.
All the procument done in SRM realted to MM only.

Through RFC

generally in SRM business partner means supplier.customer 
means enduser.
business partner means those who supply the raw material to 
the cusomer.i.e.buyer.

1 - if take referace of SRM then, In SRM all the stake 
holders are partners. eg vendor, employees etc. 

  2 - Business partner is as above, Partner function -  
make vendor as ref, then there will be invoicing party, 
suppying party, etc these are the partner fuction. for 
customer ship to party, ivoicing party etc

Supplier Relationship Management.

It Stands for...Supplier Relationship Management.

SRM Stand for Supplier Relation Management

SRM stands for Supplier Relationship Management.

It's very effective for the companies which has large 
number of users whom can directly purchase the material 
using the Shopping Cart screen for which the materials can 
be selected from the available Catalogs.

It's a extended form of ERP where data gets transferred 
between SAP R/3 and the SRM screen(vice versa)which will 
work in Internet so that the every Vendor coordination will 
be more better and which will fully avoid the paper work 
and unwanted confusions.