Because people will be coming from other activities or work, and it is a long time since lunch, the appetites will be pretty good. Also, I always make sure I have enough of everything for 1 1/2 to 2 pieces per person, especially the more desirable items; otherwise a lot of people notice that "someone else got something and I did not", which tends to put a damper on the party feeling. So, you may want to make some additions, or perhaps skip one and have more of others. For this length of time in this slot, here is what I would do:

fresh fruit, 4-6 pieces per person, fruit tray page tells how much each type fruit makes
dried fruit, 3 pieces per person
spanikopita (100), will run out
mini quiche (40), 120
apple-onion bites (40), 80
salmon spirals (40), 120
italian meats (salami etc) - 1 ounce per 10
vege tray - 2 ounces ready to eat per person
dips, 1 cup per 6-8 (more if thicker, less if thinner)

four varieties of cheese, 6 pounds
breads, 1 pound per 12
crackers, 4-5 pounds, depends on size and type

nuts, 4-5 pounds

small bowl of assorted olives. 2-3 quarts