If you have a wedding receptions with lots of activities, you should provide the DJ with a written itinerary. This will allow the DJ to understand what is happening at what times and plan the music accordingly. The DJ should be willing to work around the other events you have planned, and may even be able to provide lighting, cordless mikes and special sound effects to enhance the other events at the reception.
A wedding DJ can be one of the best types of performers to add to your reception. Not only do they provide you with music of all types, to satisfy everyone that is there, they also provide you with the ability to have an announcer and someone that will lead the evening for you.