Samuri Jack questions

1.In the Samuri Jack cartoons his symbol (don’t know if it’s his personally or his family/clan) is a circle with four inward strokes. Is this an actual Japanese syllable/pictograph, and if so what does it mean?

  1. In episode 18 he defeats the uber-robots with the help of the nerdy scientist who created them. I swear it’s the same voice as the nerdy scientist on The Simpsons, but can someone who’s caught the credits confirm this?
  1. It looks like Jeff Glen Bennett is the scientist whereas Frink is played by Hank Azaria. Certainly though Jeff must have taken inspiration from Hank.