Expect that about 85% of the invited guests will show. Only goes up if they are all family and all in town.

You need 3-4 serving lines for this many- or 2 double sided lines.

Skip one of the meat appetizers and add fruit trays (at least 1 tray for 100 from the fruit tray page). Increase crackers to at least 10 pounds or add several pounds of rye and wheat cocktail slices, tiny thin slices, great with fruit and cheese.

You could also move the meatballs to the dinner service to offer an alternative, and still have plenty for appetizers. If you do this,offer 4 pounds thin sliced provolone and a few shakers of Parmesan.

Dinner

Turkey and dressing sandwiches-not quite sure on how much.
Suggest boneless turkey breast? You need 4 ounces cooked per person, use the turkey yield tables to figure out how much fresh. If you use whole turkeys, cook ahead, chill, debone then slice, and reheat as discussed in the holiday cooking section at the top of big pots.
1/2 cup dressing per person, 1/3 cup gravy per person
1 pound cranberry per 6-8- there is a good cranberry crock pot relish recipe on this site.

Buns for sandwiches-200-250- Allow 1 1/2 standard size or 2 smaller per person, but consider having part bread. About 16 pounds per 100
Add a meatless option for the sandwiches- sliced cheese, egg salad, for the folks who don't eat meat?
chips-10 bags- you either need at least 1 pound per 15, or skip. 1 pint dip or salsa per pound
Potato salad-10 gallons which im thinking your post said about 30-40pounds of potatoes- you need only 6 gallons for this many people- about 60 pounds. Look at a few of the recipes online for roasted red potato salad, if you want something trendy that is much less work than traditional.
Baked beans-6pounds- you need 5 gallons! That is about 12 pounds dry beans, or 8 #10 cans. I would probably make at least part meatless, again for the non-meat or non-pork eaters.

I would also like to have some pop there 15-20 2liter bottles - check the beverage planning page for help on amounts and flavors

Also, add dinner level coffee from the beverage page. People really like it with their cake.