Has anybody figured out a way to modify Graph objects in Mathematica 8? In particular, how to get the same functionality you get when you right click on the graph.<
For #2, you should be able use distinguish between the two using the context. Thus, System`CompleteGraph[5] creates a new V8 graph, while Combinatorica`CompleteGraph[5] creates an old Combinatorica graph.
I'm not sure exactly what you mean in #1, but you can convert the Graph to Graphics, then the contextual menu will appear as before. I'm not so sure that this is an improvement, though.