I will try to answer some of these for you. I am sure Lauri will correct me if I get it wrong.
1. Swaps - you make whatever number of the swap, all the same, so in your example you would make 16 identical card fronts and receive 16 back. You should make an extra for yourself, if you want one.
2. ATC - They are usually 2.5x3.5 inches. This link: Splitcoaststampers - Artist Trading Card (ATC) Project Tutorial by Jen del Muro
shows you how to maximize your paper to get I think 10 out of an 8.5x11 sheet.
3. I don't know this one for sure, but in the instructions it says to load up a box of goodies you don't want and we'll swap them. I guess my suggestion would be to think how you would like the box as you pack it. Pat could definitely answer your questions better than me on this one.
4. Gift exchange - You bring one gift, wrapped. It doesn't have to be card stock, it can be any hand crafted gift. I think Lauri usually has a game planned to aid in the exchange, or we do yankee trader style. Your card holder idea sounds nice for this. I don't think directions are mandatory but if you wanted to include them I am sure your recipient would be happy for them. Be sure to include a note with your name or sign your gift so the person receiving it knows whom to thank.
I hope that helps; if I have forgotten something, or got something wrong can someone please correct me?
Lauri, I hope I didn't step on toes by answering, I know how busy you must be and hopefully I helped out a bit.