1. He got it fighting Assaj Ventress alright, but it wasn't shown directly in Clone Wars
. He fights her in chapters 18/19, but it's not until they barney it out again on Coruscant that he gets the scar. The comic SW:Republic
#71 shows the duel itself.
Clone Wars 22
shows Anakin's first meeting with Padmé after getting it.
It's alright, you can close your mouths now.