1) I would probably start with a one-shot vigilante and make all the PR's on both sides limited use so people have to be more deliberate and cooperative, and do a light theme game first. Even doing a quick game in a closed set up with a single serial killer and maybe a couple one-shot vigs would be a good transition or no knowledge of roles outside the individual's PM maybe. 2) I agree with your assessment about not being ready yet. I haven't played a ton, but I always played with hard-core types who, when you would send up a simple flare with the message hold off you are working on something, they would hold off on the lynch. I think putting people none of whom can work as a team into a heavy theme game will be a disaster that will make the work on your part not worth it.