For your quilting items, other than the rulers] it is best to have them together in some sort of carryall. I use a clear plastic makeup bag.
The more you can corral your things the less chance of loosing them or having them broken.
Be considerate of others and don't bring more than you need. That includes checking if you are allowed to bring your own iron. Many of the retreats I have been on have specifically said NO IRONS, even the small mini-irons, as they put a drain on the available electrical usage.
I usually don't take batting as I will quilt once I am home and not distracted. I tend to work only on quilt tops. Easier to take and actually finish or almost finish the work.