I am serving lunch to 22 adults for my daughters first birthday. We are ordering 4lbs of roast beef au jus from a local market which we plan to keep warm in a crock pot. We are also planning on serving 50-100 frozen meatballs (depending on size) from the grocery (gluten free) in a homemade Italian tomato sauce, which we will also use for baked ziti. We will also have home made mac and cheese, plus salad, rolls (torpedo, for beef or meatball subs), a veggie crudités platter, fruit and cheese platter, chips, pretzels and mixed nuts. Desserts include rice krispy treats, cupcakes and s'mores cookies. My questions are as follows:

We are planning on making the mac and ziti a day or two before in (4) 1/2 pans and then baking them that morning for the party at noon. We estimate 3lbs of pasta for each. Is this realistic? 6lbs pasta total for 23 people? Will 1.5lbs of each fit into a half pan? (2 half pans per item)? Is an hour or two enough time to bake 4 half pans in the oven? Should we use the shallower pans or the deep ones?

Do we need a vegetable or is the salad and appetizers sufficient? If we need a vegetable, what would you recommend for minimum prep time/effort? I have access to several crock pots, but limited culinary skil.

Should we heat the meatballs up in the oven before transferring to crock pot or can they all go in the pot once thawed if the sauce is warm? I ask only because we have limited transport/storage capability so the fewer individual items, the better.

4lbs of roast beef au jus - if this is self serve, I would not do less than 5, or even 6. Leftover roast beef is a pleasant outcome.
meatballs- 3-4 pounds, 1 quart sauce, Need to be hot when they go in the pot. An old fashioned electric frying pan or 6 quart Nesco roaster is an option...

home made mac and cheese, ziti
You need about 5 pounds total, so 6 is OK, divide according to family tastes; 1 quart sauce per pound, 1 /2 to 1 pound cheese per pound. Most people like the shallower pans, because of the crispy edges. A full pan will hold about 3 pounds plus sauce. Cold, 2 hours, first 1 1/2 covered is plenty; when they reach 165 in the middle, turn the oven to 180 to hold.

salad, 1/4 the amount for 100 on the plan for 100 page- discusses dressings
rolls (torpedo, for beef or meatball subs), 2 dozen

veggie crudités platter; with the salad, suggest you skip this and do a sandwich condiment and relish tray with various pickles, sliced tomatoes, lettuce leaf, maybe olive salad? See classic relish tray on the veggie tray page for ideas, or the sandwich trimmings list on the sandwich page.
2 boxes Parm, bottle spicy mustard, bottle ketchup

fruit and cheese platter, 3 pounds fruit, 3 pounds cheese, some sliced for sandwiches

chips, 1 1/2 pounds, 1-2 pints dips or salsa
pretzels, 1 pound
mixed nuts, 1 1/2 pounds

Desserts
rice krispy treats,
cupcakes
s'mores cookies
1 of each, not too large, per person, plus a few extra s'mores
add dinner level coffee (1/4 amount for 100)