If you want to cover Cadiz, Ronda, Seville, Cordoba and Granada, you are going to have difficulty doing that if time is short. It probably is easier to start in Seville, and work your way in a circle to cadiz/ronda, then granada, leaving cordoba for last where you have that AVE you can take back to Madrid. It is also probably the one city to skip if I absolutely had to eliminate one from the Seville-Cordoba-Granada triad, or at least its the city where you could spend the least amount of time in (no offense to the Cordobeses!!)
Booking ahead is reccomended for Easter week though I am not sure how easy that is to do on-line....a travel agent may be more helpful.