Jack was certainly to blame too but it was Will's idea at first and he didn't seem to like it. Will was the one who endangered those people (and didn't even flinch facing all the bodies), Jack was just bad at his job. They never learned their lesson!

I took the cleavage as a bit of a shout-out to Claricie's dress in the Hannibal film
I didn't think of it but you're right. Even her looking so high recalled drugged Clarice.