I suspect the A3 is just not as quiet as it's supposed to be. I had a Volvo V40 and Seat Leon before I don't find the A3 any quieter, but not louder either roadnoise wise from tyres. Wind noise I think the A3 is pretty quiet at highway speeds, when the highway is smooth surface! Can hold a conversation with all passengers. I had Bridgestone on the Leon and Michelin Primacy 4s on the V40. However they were 205/55 R16s and the A3 is running 225/45/R17 (Pirelli P7 C2). Maybe your car just is an S line with less suspension and a thinner sidewall 40 profile. Had a courtesy A5 running 245/40 R18s, and that car was quieter both wind and road noise (well it better be it's more expensive!)
In regards to the wet grip, I have no issues, during one massive thunderstorm in August, massive rain requiring wipers to be on high and it still wasn't fast enough, going 65mph on the highway it was fine.