I think that using VertexFrame subtypes is the right idea, but I don't think that we need to worry about the JBDS plugin yet at this point. I don't see any technical blockers to doing the first part and then building the API for the Eclipse plugin later, which would need to provide a more specialized approach anyway and as you said, should not be tied to the Model types.
I think that manual conversion is the way to go. I think that dealing with annotations in this particular case would be too complicated for the "benefit."
First approach I think is good. Though I guess it depends on what types you're talking about specifically. Simply adding the types is not enough - we also need to add rules that will populate the graph with these types/interfaces.
~Lincoln