Congrats! You may want to be careful putting out potato salad for a length of time (outside in June). You may have to keep it covered and on ice so it doesn't spoil. I errored on the side of caution and made garlic salt potatoes for my sons party a few years ago. It was a lot easier too. I cooked 30 pounds of small potatoes for 100 people and served it in my roaster with butter and garlic, and we had plenty.( It stays warm for a while, and people loved them even when they got cold!). You could also use regular size potatoes and quarter them, but they tend to break apart when you stir them. As far as drinks go, don't forget the bottled water! I ran out! I had gallon jugs of water also, but everyone wanted the bottles so they could drink some, re-cap it, then go back to playing football, volleyball, etc. ( I had cases of soda left over). The number of drinks per person may depend on the weather (how hot or cold it is) and how long your party is. I hope this helped you. When I had my son's party, I didn't have the internet and it was all tial and error. My youngest graduates this year so I'm using some of these tips and websites, along with some experience this time! Good Luck!!