Your family sounds like my kind of people. Personally, I would suggest getting some sliced roast beef, ham, etc. and cheeses from the deli to go on the little dinner rolls (also a variety) with a variety of mustard, mayo, butter, horse radish, pickles, olives, etc. Add a nice pasta salad, baked beans, vegetable platter with dip, chips, carrot salad....you get the idea. You could ask some of the closest family members to bring some of those dishes. The rest you can order from the deli section at the grocery store. Don't try to do it all yourself, but you be the one to organize and make sure that all the pieces are fit together.

As for the cake, I would suggest concentrating on ordering a really good cake concentrating on taste rather than fancy dancy ornamentation. To me it is a shame to decorate to the hilt something that tastes ordinary. Have a bakery make some suggestions and see if they have a sample of what they would suggest.

I would also make sure you have a good variety of beverages to go with the food and coffee for the cake. Flatwear, dishes, napkins, and have your camera ready for plenty of pictures so you can make an album for remembrances of the occasion.