Integrating SAP CRM to Portals

Hello SAP CRM Gurus

I hope you are all well. I have been requested to prepare a demo of integrating SAP CRM to SAP Portal for a client next week !!

Please can you tell me any advice that will assist ( cook book ?) . He wishes to find out about , in particular,

1) Authorization models in each system

2) how to pass data between the systems

3) any problems that may occur during the integration

4) Question that client is asking my manager is why do we need Portals when we have sap web gui -he then asks me - any help much appreciated

I am from CRM background so this is new to me - many thanks in advance

Regards

Raj