You've just cracked why he's older now.It's kind of silly to complain about a District Attorney being 40 something. He's an Assistant DA in his mid to late twenties. It makes perfect sense in context.
I don't care so much about Bruce and Harvey's relationship. I care more about Gordon and Dent's, and we're going to see it unfold in grand fashion, and probably not without their share of conflict. I can't wait.