I am looking for a simple way to create a button to "Convert" records. To be more specific I need to layout our current Zoho structure.

1. Contacts: Any contact our organization wishes to track. They are not yet established as a 'Lead' and may always remain as only a contact we wish to keep stored within the CRM.
2. Leads: A Contact or Organization that our company has identified to bring potential deals to us.
3. Opportunites (Deals or Potentials): Potential deal or project is now on the table and we must work it through the pipeline to Closed Won.
4. Customers (Accounts): An organization or person that we have established revenue with OR have a signed contract with.

The reason I need to lay these out is because we intend to convert Contacts to Leads....Create Opportunities from those Leads...and close Opportunities and bill to create Customers. I am looking for a way to do the following:

• Easily convert from each of these modules
•       (Desired) information to be transitioned to the converted record
• Contacts to always remain even after conversion
• Leads disappear once converted to an Opportunity
•       (Desired) information to be transitioned to the converted record
•       If Lead is converted to Opportunity - there is NOT a Customer (Account) created for them because no revenue has been established yet.

I appreciate any and all help 

Trevor