I will also have a 5-8 lb fruit tray, and two large trays of very rich noodle kugel.

As guests arrive I will have cheese, pâté, crackers/breads, hummus, and creamed herring to nosh on until we get a critical mass.

At the end, assorted desserts.

All day, coffee, tea, juice.

It looks to me like a very abundant menu, and I would expect you to have leftovers.

Bagels (#) 1 whole per person
Lox (by weight) 1 pound per 5
Cream cheese (by weight) 2 1/2-3 pounds
Tuna salad (by weight) cant do; about 1 cup per 5
Egg salad (how many eggs)3 dozen
I would add a few tablespoons of capers to garnish the salmon