Stay as long or as little as you like. No need to bring anything. The coffee shop does have free wi-fi if you decide to bring your laptop. The agenda is flexible and can include whatever topics, questions, or concerns you'd like to discuss.
My vision for this group is a place where WordPress Developers can come together to discuss, ask questions, share ideas or get some assistance with any development difficulties one may be experiencing...or just to talk about WP development in general.