Paul's stick, and third "young" man at meal
A bit of Googling suggests that Robbie Coltrane now needs to use a stick in real life, but has there been any indication in the series as to why Paul does? Infirmity, weight, accident? It does add a touch of vulnerability to his character.
And who was the third man at the meal where one of them touched up the waitress? One was young Paul, another young Karl.
BTW, I was a bit surprised at the girl's reaction, which seemed to combine amusement with almost delight - presumably that a TV personality had given her some attention.