Chester "Chet" Burrell, the new chief executive officer of CareFirst BlueCross BlueShield, is setting an ambitious agenda for himself and his company. His goals include designing new health insurance packages to cover the uninsured, finding ways to reward doctors and hospitals for good and efficient care, controlling medical costs, and building a secure system of electronic medical records. CareFirst has 3.2 million members in Maryland, the District of Columbia and Northern Virginia.