Questions for Kagan

George Will is in the house and Newmark's at the Door:

If Congress decides interstate commerce is substantially affected by the costs of obesity, may Congress require obese people to purchase participation in programs such as Weight Watchers? If not, why not? . . .
If Congress concludes that ignorance has a substantial impact on interstate commerce, can it constitutionally require students to do three hours of homework nightly? If not, why not?
Can you name a human endeavor that Congress cannot regulate on the pretense that the endeavor affects interstate commerce? If courts reflexively defer to that congressional pretense, in what sense do we have limited government?

Should proper respect for precedent prevent the court from reversing Kelo? If so, was the court wrong to undo Plessy v. Ferguson's 1896 ruling that segregating the races with "separate but equal" facilities is constitutional?