Stubborn, Dooku trained for 13 years under Sidious until Anakin killed him. Have you seen episode 3? Sidious says to Obi: You can't beat him, he's a Sith Lord (about Dooku.) Want official proof? Here's a link. Read it and the EU part on Darth Tyrannus AKA Count Dooku.
http://www.starwars.com/databank/character/countdooku/?id=bts
Nope. Dooku is a Sith lord. There is always two, and Dooku was the filler for ten years. Dooku doesn't have yellow eyes because the concept was actually reintroduced by KOTOR which was made after AOTC and then caught on by Episode III. But Dooku has a Ruusan crystal lightsaber (red) and uses Force lightning. His hilt is Sith style. He IS Sith.