The Dragon of Wind is Raimundo. 'Rai' means 'Thunder' in Japanese. Throughout season two of the show, Raimundo's main attack is called 'Typhoon Boom' and sounds like thunder.
The Dragon of Fire is Kimiko. The Asian character 'ko' (shaped like the letter K with a line at the side) means 'fire.'
Originally Chuck Norris was going to have a guest voice of a character who inspired Clay Bailey when there were plans to make a fourth season. However that plan never came to be as Kids WB wanted other new shows.
Warner Bros. Animation released a pilot to a show for Kids WB called "Knights of Sherwood" online, that was similar to Xiaolin Showdown. If the pilot were to become a show, there was a plan to have a Xiaolin Showdown and Knights of Sherwood crossover episode where the monks travel back in time and team up with the knights to defeat a young Chase Young who has teamed up with the evil king who is the knights' arch-nemesis. However the pilot never came to be a actually show as Kids WB was starting to lose it's audience due to the rise of shows on cable kids networks like Disney XD, Nickelodeon and Kids WB's brother channel Cartoon Network.