With no caterer, how do I arrange to get the food on the table?

Ask the venue if they will provide people to heat the food, lay out the buffet, pick up plates and gles as guests finish, and then clean up. You'll have to pay, of course. Alternately you can ask the restaurants where you're getting the food if they have someone who could come out and work. If you offer a good wage plus a promise of a good tip for a job well done, you'll get plenty of volunteers.