What are the limits of Mage’s Magnificent Mansions?

I am DMing true D&D for the first time. So far it has been one of the most fun experiences in my life. However, I have found myself in a bit of a pickle. Starting off I was very liberal in what I allowed my players to create and do, and now am seeing the problems of this break out in my world. So, now I am tightening the leash a little bit. One player in particular has a very powerful Rakshasa sorcerer and recently has started using the Mage’s Magnificent Mansion spell to create a restaurant and sell the food from inside. He is trying to weave a network of mansions from different points together to create a instantaneous fast travel system. The player states that the rules are genuine, but I’m not so sure it I agree. Are there any limits to the this spell in the rules? Can he have more than one mansion at one time and can his servants leave the mansion to act as staff in an eatery?