I have read somewhere that Vue doesn't support multiple Poser runtimes. I found that the hard way when I upgraded from Poser 6 to 7 and I wanted to keep both runtimes separated. I started having a mess with Vue imports, I searched for it and I found in some knowledge base (e-on?) a specific note saying that.

Regarding reimport of Poser characters, I have V6I and I just save the Poser file again and Vue automatically asks me if I want to reload the character. It's reloaded in exactly the same place as I had placed the old one in Vue. Of course, I can not break the connection to Poser by manually changing anything, like ungrouping or such. If I do that, I do a very simple trick: I center the object I want to replace, in all views, I delete it, and without changing anything, I reload the new character. Choosing the option "center object", it goes to the exact same place as the old one was.