Customer Portal - More user information and broader permissions

Customer Portal - More user information and broader permissions

Hi,

I'm investigating how to use the Customer Portal within an application.   

I understand the Sign-Up page (Name and Email address ) fields cannot be modified.   However, in trying to capture additional information about user preferences and their company (which some of the information would also be contained within Zoho CRM.
  1. Is it possible to capture more information about the customer outside of the two key fields?  And what is the best way of doing that?  I have assumed it would be to create another Form and link the user as a disabled field? 
  2. Is it possible to provide customers with broader access to their companies records (ie.. records on users who also work for the same organisation) through permissions?  
  3. Finally, in terms of integrating back with Zoho CRM to capture and update common details. Is the best way to match records and update with a deluge script?  Since the "integration" appears to provide a drop down option which is not acceptable for external sharing. 

Thanks and appreciate any help,

Andrew