Some rabbitholes change the lot type when they are placed in the lot, meaning you don't have to make it "bookstore" (it doesn't exist, it's just an example). Others don't even need a specific lot type, just being Commercial is good enough.
You can put as many independant rabbitholes as you wish in a lot; For example, if there were 1500x1500 lots, you could place a bookstore, a theatre, a grocery store, a hospital, a business building, a city hall, a military building, a science facility, a school, a stadium, a spa, a restaurant, a bistro, a police department and a criminal headquarters in the same lot and they would all work. You wouldn't be able to place a mausoleum, though, as it changes the lot type to graveyard.