In relation to the question of how Lolita knew Humbert's address, Lolita had kept in contact with Mona in the screenplay version in the book.  Mona had corresponded with Lolita and Lolita probably knew already through Mona that Humbert was still at Beardsley (in the screenplay).  Mona would have still been going to the girls school at the time, assuming she was Lolita's age, perhaps Humbert's mail was forwarded from his Beardsley mailbox to his current address--and Mona knew this?  Or perhaps Nabokov created this story to suggest a contact theory like the Farlow one.  I'm not sure how college mailing systems work, but perhaps that might lead to something.

And one other thing, in the chapter where Humbert receives Dolly's letter, he mentions two other pieces of mail.  The one that interests me momentarily is the letter from Rita's mother, "a crazy little woman, whom we had visited on Cape Cod and who kept writing me to my various addresses" (Annotated Lolita pg 265).  How was she following Humbert's address?  It was not through either Beardsley or Farlow, so there had to be another way.  And perhaps these two instances (Rita's mother and Lo) are connected in method.

Logan Norris