I have always said that if I was the one to award the Oscars for 1931, it would have been Bela Lugosi for Best Actor and Dwight Frye for Best Supporting actor. He was a really underrated performer and I often wonder what would have happened if he had not had a heart attack and gone on to play the role he had coming up.

As nOs4a2 rightly says, the book makes it clear that Renfield (who was a quite different character from Harker and did not visit the Count in Transylvania) was a member of the "household" and thus could ask him in. His actions and comments to the doctor, while at first distract the doc's attention, later give credence to a rather unscientific theory--that they have a vampire at work.