I am planning my sons first birthday we have
80 - adults
25 - kids
6 - babies

We are serving Hamburgers and Hotdogs - main food
Potato salad - 20lb bag of potatoes
Broccoli salad
Mac salad
Green salad
Potato chips

I need help with the following quantities.

hotdogs and hamburgers
tomatoes, lettuce and onions for burgers
green salad
broccoli salad
Mac salad

I plan on having 16 gallons of punch and tea and 8 gallons of water.

hotdogs and hamburgers
Jennifer, hotdogs are a real choking hazard for kids! Would you consider doing sausages and peppers, or meatballs, either of which could be done ahead, instead?
Anyway, about 110 hamburgers and 10-12 pounds of whatever second meat you choose
Buns or rolls per your meat choices
gallon assorted pickles and relishes
tomatoes, lettuce and onions for burgers- see the sandwich planning page, also mustard and ketchup
green salad- see the plan for 100 , salads and dressings
broccoli salad- 2- 2 1/2 gallons
Mac salad- 6 pounds dry pasta
With so many kids, consider adding a fruit tray, the deluxe tray for 100 on the fruit tray page would be plenty
Consider adding about 8-9 pounds chips and 8-9 pints dips/salsas

Beverages fine, consider lemonade or a non-red punch to simplify spills.