The director does much more than simply cast and direct the actors in the play. They have production meetings with many different people such as the lighting director, stage manager, set crew, and many more so that the overall feel of the production is coherent and consistent.
There are also many different types of directors, some are very spontaneous and will add and subtract things all throughout the show while others are more organized and direct. Many follow the organized route because directing is strenuous as it is. According to Jeanne Sanner there are ten steps to directing a play:
1. Know the play
2. Design the set
3. Design the blocking
4. Establish rehearsal schedule
5. Establish support team/assign tasks clearly
6. Create audition information packet
7. Cast the show
8. Establish a professional attitude through example - RESPECT
10. Put things in perspective - Share a lot of love and have a lot of fun
But then again that is only one professional director's opinion. For instance a lot of directors who do performances with college level actors establish the rehearsal schedule after the show has been cast. Each situation is different in directing which calls for different and specific needs.
For more information on directing go to this link: Directing