Setup Custom Purpose: Go to Organization Administration, Setup, Global Address Book, Address and contact information purpose.
Setup Customer with distribution based on Customer Contact: Go to Sales Ledger, Common, Customers, All Customers
Setup Company Specific Document Handling Rules: Go to Sales Ledger, Setup, Forms, Form Setup
Since it seems this thread would use purpose on the contact, I encourage you to vote up this idea on the ideas site. As it deals with showing the contact's purpose directly in the contact grid without need to click advanced to see this. It is already done for the Address. To me this should be standard for contacts as well. Thanks!
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