You can use the DSL tools in VS2010 in order to create a Minimal WPF language designer that will consist of all the model elements you require (classes, properties and etc.) and will be WPF-databinding enabled - that means that you will be able to create a "custom graphical modeler". In the end you will get a VS editor as an extension that will be tied to a specified file extension.
Just something to bear in mind - we didn't intend the customer to use WPF minimal language to create a fully-fledged editor and as a result it can be quite difficult (although possible).
In regards to generating additional artifacts from the model - you will be able to write t4 templates that can generate anything you want according to the model (or any "templated" textual thing in general).
See more info in DslTools page on the code gallery (http://code.msdn.microsoft.com/DslTools) and the Lab (http://code.msdn.microsoft.com/DslToolsLab).