Will there be enough seats?

Short answer: Yes.
Long Answer: We try to provide as much space as possible inside as well as outside of the hall. Anyway, you should use space economically. While the hall looks rather empty in the beginning you might observe that it fills up continuously, as some visitors can only attend later, due to personal reasons or long travelling distances. Just pick yourself a nice place that isn't taken, but keep in mind that there will be other visitors that might need some space too. By the way, not everybody arrives with his computer.