1. The model is a little rough around the edges, but it could provide a good starting place, if you're willing to edit it a little.
2. Well, if you're willing to make heavy edits to a converted version, no one will care. Even better if you make your own model using the JJ3 one as a reference, which will probably make things a little easier anyway, since the JJ3 Jazz model was never boned properly.
3. It's very easy to Google.
4. If you can convert it to a compatible format, it'll work fine.