AD FS and forms Authentication

We have an ASP.NET Web Forms(.Net 3.5) website application uses forms authentication. The application has got different customized authentication services which uses different SSO methods(eg. CAS) to validate user, those were implemented for different clients. Now the requirement is to implement an AD FS based authentication service with out making core changes to the Forms Authentication configurations.

My questions:

1. How to configure SAM in .Net 3.5 website
2. Instead of redirecting to STS, is it possible to pass user name and password from my login page to AD FS proxy and get saml response?
3. My intention is to read a custom attribute value(eg. Employ number) from the saml response and proceed with the current authentication module. Is it possible?

This question is based on a discussion in AD FS and forms Authentication, any help will be greatly appreciated.

Sreekanth Mohan