I'm not sure I want to be 3betting A4o here. I might 3bet every suited Ace but that's a completely different story really.

As for the flop I'd suggest you look at what your 3betting range is in this spot. I imagine it's strong enough that you don't want to be calling w/2nd pair when that 2nd pair is 4s. So many hands, even those with no made hand have lots of equity against you and lots have you pretty well beat.