Here in Switzerland, hand-shaking was even more common than in the US. It was expected of everybody. School children would even shake hands with their classmates and teacher before leaving. Covid cancelled most of that, and it’s far less common today than it was.
Panel 4, it looks to me as if Marcus has just spotted something which really alarmed him. Those eyes are not directed at Dick despite the questioning. He saw his killer coming but didn’t say anything, like deer in the headlights.
I like the drawing style too. It feels like a throwback to classic things like the old Dick Tracy TV cartoon series. I wouldn’t want it as the normal style, but it makes a pleasant change for a while.
Sorry, not getting the joke here. Something specific to American English?