The Justices decide which cases they will take.
They can easily be on the look out for a case and take it if it will give them the opening they need to reverse Kelo.
Yes, but according to Sandra Day O'Connor - again from the same seminar I saw - they should only take cases in which there is a conflict in the lower courts. Each Justice votes yeah or nay on every case brought before the court and one of the crition should be a dispute at the appellate court level.