The following are my understanding on CRM Software application-
1. We can have MVC/ASP.NET options to create an application, MS Sql server can have database choice to save all data.
2. To handle client validation we can have javascript/jquery which can restrict user action and provide compatibility.
3. To provide neat look and feel, we can have CSS/CSS3 styles.
4. For Lead Management we can cover Create Lead, Build a List,Create Lead from VCard,View Leads,View Lead reports and import leads.
5. For Contact Lead we can cover create contact,build a list,create contact from vcard,view contact,view contact reports and import contacts.
6. Automatic Address Book,Lightning Fast Search module we can manage with AJAX async request that will fetch faster data.
7. Tags, Notification & Following we can have available API's that will establish linking between social media.
Now, i have started myself as a full time freelancer to serve you better in delivery and project manageability.
We can have more discussion for clarifying missing part.