1: We learned that purposeless move in the opening are, well, purposeless, don't use/play them. Maybe h3 had been a nice move if the plan had been a pawnstorm on the kingside, but that never happened, so the move was pointless, Bg4 or Ng4 would probably never be played any time soon and it even weakened the king-side prematurely.
2: We learned that being greedy is not always good, not even when there is few pieces on the board, for example even my computer suggested Bf8 as prophylaxis instead of winning two pieces.
3: We learned that castling early is not a neccesity, in fact, my computer saw little need to do this before move 16 or so. Castling had maybe lead to a king-side pawn storm regardless of where the white king was.