LOTS of positions open. CS bachelors degree from a good school is enough to get an interview, though a masters is obviously a surer bet. Not sure about the actual interview types, but the harder part is actually get the security clearance. Be prepared for a process that will take 6mo to 2 years, involve drug tests, credit reports, talking to your friends, coworkers, employers etc, and a polygraph exam (possible covering personal behavior (including crime, sex, drugs, mental health, finances etc.)