Question: In the end it seems like they were going to end the series, saying bye to Rudy and them leaving, being all upset. Why did they try to end it, then start it back up with a different dojo?
Answer: I think they must've thought Rudy was leaving town for a few years. Either that or they were originally ending the series.
Question: Does anybody know what happened to Eddie? He just vanished in this season.
Answer: No, it has not been explained where Eddie went; the characters don't even mention him.
He went to a dancing school.
In the "oh christmas nuts" episode it is implied that he left the dojo because he was not as physically capable as the others.
Answer: The character who plays Jack told everyone that the character who plays Eddie went to go to see her grandmother in England.
Answer: This was intended to be the series finale but it was so popular at the time that a fourth season was added after this episode was filmed. Adjustments had to be made to film the new season including a new set and compensating for missing cast members.