The Meaning of Baptism in the Bible

There is much confusion over the meaning of baptism as practiced in Christian churches today.  Who should be baptized?  When do you do it? (in infancy or adulthood)  Where should I be baptized and how?  (sprinkling, pouring, or immersion)  And most important, do I have to be baptized to be saved?  We had a baptismal service at our church where I answered those questions in a sermon.