How tall is a standard serving table?

They stand taller than a normal dining table. Most sit around thirty-four to thirty-six inches high from the floor. This height meant servants could carve meat or pour wine without bending over. It keeps the food at an easy working level.

What goes in the middle drawer?

Cutlery usually goes there. Many original serving tables have baize-lined sections inside the central drawer specifically for knives and forks. They're shallow because you don't need much depth for silver.

I want to put one of these in my hallway as a console table, will the proportions work for that kind of space?

A serving table often works well in a hallway. They share the same long, narrow footprint as a console table. Because they were built to sit flat against a dining room wall, the back is flush. The main difference is the height. Serving tables are quite tall, so you might find you need a larger mirror or painting above it to balance the proportions on a hallway wall.

Why do some of the brass rails on the back have small threaded finials that unscrew when you try to turn them?

Those threaded finials are a practical feature for cleaning. Brass galleries tarnish quickly in a room with coal fires and food steam. Servants unscrewed the finials to remove the entire brass rail in one piece. They could then polish the metal away from the table without getting abrasive cleaning paste on the mahogany surface.