Will questions about various biker groups and biker clubs be on topic here?
I think this will be one of those areas that falls under "it depends". Clearly some questions relating to MCs will be relevant, but some questions around them are likely to have absolutely nothing to do with motorcycling apart from the fact that it involves an MC. For example, I don't think the following would ever be regarded as "on topic" if this site goes live:
"What is the primary means Club X uses for raising funds?"
I'm a moderator on a couple of other SE sites, one of which (Retro Computing) deals with a surprising number of questions that spill over into meta discussions as to whether they're a fit or not, often because everybody's definition of 'retro' is completely different.