Ooh, yes, Polly, you were wondering the same things and coming to the same conclusions! I thought Faraday's greed for the Hall and the lifestyle it had represented to him as a child, was creating some kind of poltergeist.
I don't think he was conscious of it, but do you remember Gyp's attack on the Baker-Hyde child came just after Faraday realised he was just a makeweight at the party and Caroline and her mother were setting out to catch the rich bloke.
Gouging out the acorn as a child seemed very significant because he was damaging the Hall in his desire to possess it.
Nothing really happened until he started visiting. Betty complained the house was so big, empty and lonely that it frightened her but she didn't say anything else.
Then, of course, there was the nightmare that he was rushing to the hall the night Caroline died. And she recognised someone when she was running away.
He seemed increasingly deranged towards the end, urging Caroline to stay at the Hall when any normal fiance, even if they thought the supernatural stuff was hokum, would be encouraging her to leave because of all the horrible memories, not to mention the fact it's becoming increasingly uninhabitable.
And then the end, when he wonders about the ghost, and sees his own face.
I didn't pick up on Faraday/conductor at all. That was clever of you.
But, yes, I'm sure he was causing the little stranger and I think he remained unaware of it.
I did love it being so open-ended. I think the best spooky stories are never cut and dried, but leave lots of unanswered questions.