Is vomiting sufficient after I find out that there is alcohol in the food, or must I do something else?

You did well by vomiting the food you knew contained alcohol. You have an example in the actions of the Companions, for Abu Bakr vomited food that came to him from ill-gotten wealth, and Umar vomited milk from the charity money. Also, whoever drinks alcohol must vomit it. So, nothing is required of you other than what you did.