Asterisk installation, configuration and basic customization

I am developing a web application that needs to interact with ASTERISK NOW PABX. My preferred environment for the front end is ASP.NET/C# with MS SQL. But I am open to whatever is best to achieve the needed results in a professional manner, and we can not integrate both systems. I need help with installation and configuration of the system. The pages on the front end will only need to have the basic functionally, the full customization, with a full normalized database won’t be necessary for this phase. This system must have these capabilities initially: 1. Multiple managers (Site owners) and multiple customers. The system will basically act as a bridge to secure owners privacy during communication, with call forwarding or conference call. The customer will never call the manager directly; the system will record the call and send to his manager based on the customer ID. If the manager wants to call the customer, he does so through the system, so his real phone id will never show to customer. The main reason a customer will contact a manager is to request a service when the product breaks. If the call is for service request, the system will also send the recorded message to the service provider phone number and email. 2. Send voicemail to email as detailed above 3. Managers can listen to voicemail on web (Inbox) 4. click to call my manager ( System will call customer and then call manager to connect the 2 parties) 5. click to call this customer ( System will call manager and then call customer to connect the 2 parties) 6. Payment reminder calls and emails will be automatically sent if customer didn't pay on due date. 7. Accept payments by phone. After a successful payment, payment table will be updated. Thank you email will be sent 8. Automated Attendant (see below) Automated Attendant: Thanks for calling “company name” Enter your ID. For customers: 1. make a service request 2. make a payment over the phone For manager: 1. listen to voicemail 2. call a customer by customer id Payment will be done as following: 30% As the system is installed and running 70% when job is 100% complete and fully tested. extra features will be added as the project matures.