Can a DirectX surface be plotted to a WPF control?

Yes it can. It's usually quite smooth, because WPF itself is an implementation of DirectX.

See MS' Greg Schechter blog:

Redirecting GDI, DirectX, and WPF applications

You can also have a sample of D3DImage on a surface on WPF from Codeproject: http://www.codeproject.com/KB/WPF/D3DImage.aspx