First, to answer Angelbrz, this conference is in-person only. We may record some sessions and put them on YouTube for viewing later, but for now, it's just in-person.
As for hotel rooms, the group rate applies if you stay all or part of the conference time. It also applies to the three days pre and post event in case you want to stay additional time. So feel free to book for as little or as many nights as you want, just do so in the next two days as the 24th is the last day to access the group rate.