Yes form builder 2 includes the functionality of Validation Toolkit, Universal Email, Digital File Pro and HTMLEditor. It replaces those extensions.
They should not be installed, only install form builder 2.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.