1. Most Senators don't seem to care much about the answers to their questions. Rather, they are using the questions as a place to expound their own opinions.
Senator Frist, or should I say Doctor Frist, repeatedly talks about how he is a doctor and delivers babies. I heard a speech by him on NPR where the topic was health care, but most of the speech turned out to be on the topic of his private medical practice. (He repeatedly talked about how everyone deserves access to health care, but his solution was more technology and tort reform, two things guaranteed not to work.) Perhaps he thinks people generally trust doctors more than others and this will help him become President. I hope not.
2. Judge Robbers avoids answering questions that would not prejudge future cases by saying that answering would prejudge future cases.
Answering whether you believe their is a right to privacy does not prejudge any particular case that might come before the court.
Answering what test to apply when determining whether congress has gone beyond its power to pass legislation under the Commerce Clause or the Fourteenth Amendment does not prejudge any particular case. To say otherwise is a dishonest dodge. Its understandable he does not want to say things that could get Senators or interest groups upset, but he should not claim that he is obligated not to answer because of a duty to analyze future cases fairly. He could even preface his answers to say that he could change his mind on the test and that each case is different, but explaining one's general philosophy of interpretation does not prejudge cases. Following his logic, the Supreme Court could never publish their opinions because it would prejudice their future opinions.