Thanks for encouraging people to write their first post, I resonate with your words.
As for introducing yourself to the forum, people are encouraged to introduce themselves in the open quarterly threat I believe, see the current one. That might be a cleaner solution than writing lots of small introduction posts.
For the history leading up to machine learning I would recommend A Brief History of Artificial Intelligence by Michael Wooldridge
I encountered both types of participants (the ones that showed up because they had 'not much better to do' and the ones that are not used to committing). My impression was that most participants were ambitious and that they liked a challenge. The effect of the length of the event on potential participants with varying levels of ambition can be a bit ambiguous here. With a longer event it is also more likely that potential participants have other things planned during part of the event. My gut feeling says that making the commitment bigger than a day for an introduction hackathon (without coding) makes it less likely for people show up.
Could this also be a good opportunity for pages written in languages other than English?