I agree that Marcus probably would have at least known Astoria socially, though the age difference makes it a little more difficult for them to have really connected. I have a feeling they'd being extremely proper in their interactions, at least until they can establish something more than the superficial.
Marcus is perfectly willing to carry on a conversation with Megan, but he probably won't start it himself. The intimidation factor is something he's gotten used to, and he doesn't let it bother him anymore, and just tries to get past it as best he can.
Oh Oliver. I'm totally okay with a banter-filled friendly rivalry - I imagine one that's not actually terribly serious but that the press likes to play up whenever their teams meet?