1) Differences...
"The Microsoft .NET Framework 3.0 (formerly WinFX), is the new managed code programming model for Windows. It combines the power of the .NET Framework 2.0 with four new technologies: Windows Presentation Foundation (WPF), Windows Communication Foundation (WCF), Windows Workflow Foundation (WF), and Windows CardSpace (WCS, formerly “InfoCard”). Use the .NET Framework 3.0 today to build applications that have visually compelling user experiences, seamless communication across technology boundaries, the ability to support a wide range of business processes, and an easier way to manage your personal information online. This is the same great WinFX technology you know and love, now with a new name that identifies it for exactly what it is – the next version of Microsoft’s development framework."
Basically, .NET 2.0 with some knobs and whistles...
2) Yes, it's installed by default with Vista.
3) Link for more info...
http://www.netfx3.com/
"The Microsoft .NET Framework 3.0 (formerly WinFX), is the new managed code programming model for Windows. It combines the power of the .NET Framework 2.0 with four new technologies: Windows Presentation Foundation (WPF), Windows Communication Foundation (WCF), Windows Workflow Foundation (WF), and Windows CardSpace (WCS, formerly “InfoCard”). Use the .NET Framework 3.0 today to build applications that have visually compelling user experiences, seamless communication across technology boundaries, the ability to support a wide range of business processes, and an easier way to manage your personal information online. This is the same great WinFX technology you know and love, now with a new name that identifies it for exactly what it is – the next version of Microsoft’s development framework."
Basically, .NET 2.0 with some knobs and whistles...
2) Yes, it's installed by default with Vista.
3) Link for more info...
http://www.netfx3.com/