yea, your good, thats the first one, by the second series he's already zero and he's already formed the black knights.
The second season is called like R2: The second reveolution or something ( i can look it up when i get home.)
your on the right one, series starts with CC getting rescued from that prision truck, and then getting shot and giving Leluch the geass.
Poor C.C, they really play up her immortaility and healing factor, she gets shot, cut up, burned and everything else at an alarming rate.
IT's not easy being an immortal witch somethimes i guess
EDIT: just to clarify, it ran 2 seasons total for a grand total of 50 episodes. Your on season 1, which should end at episode 25, then thier is a seconed 25 episode season that picks up the story and finshes it.