Jeezy is talking about how much he pays for a pound of cocaine. Paying less is a status symbol; it means he's farther up the drug ladder. He used to pay 24 (Kobe Bryant's jersey #) and now he pays 23 (LeBron James). Compare to JayZ in Empire State.
The lady in question is complimenting Kanye, suggesting by his personality that he 'rocks.' At the same time, the line also suggests she is referring to his label Roc-A-Fella records, acknowledging the iconic logo 'charm' his necklace bears.
Jake is slang for police, derived from the old TV show Jake and the fat man. While he was selling cocaine he escaped from the police that were in pursuit.
When he was 12, Wayne shot himself in the chest with his stepfathers gun. If the bullet would've been two inches closer to his heart, he would have died.