Bob Brown explains the fix for my HitTest problem. the fix was to switch from Viewport3D.Models to ModelVisual3D/ModelVisual3D.Content ... don't ask. that switch returned a Ray3DHitTestResult to the HitTestResultDelegate instead of a PointHitTestResult ... don't ask. would have never figured that out. anyway, the Ray3DHitTestResult allows you to figure out which Model in the Viewport3D was selected. now i've got a small Z-Order problem that i could look into and then move on to adding navigation.
so what has transferred from my past dev experience? the eventing model, data binding, and working with Controls transfers over from WinForms. working with Managed DirectX to understand 3D concepts was critical for Viewport3D. the declarative model from ASP.NET makes XAML more approachable. SVG transfers over to some of the lower level elements, but WPF supports alot more. i dont actually know Flash, but i think having that dev experience would be beneficial. my assumption is that past experience with Flash would transfer over for working with layouts and animations.