Jim Pierson's listing as a consultant on IMDb is fairly recent - but so far as us knowing he filled that position, we've known since this message was posted on the MPI's Web site back in '08:
this is from the article "Johnny Depp to Portray the Angst-Ridden Vampire Barnabas Collins?" at http://mpimedia.com/wp/?p=19 --
Producer Jim Pierson of Dan Curtis Productions and MPI Media Group will serve as a consultant on the project.
Though the message has long disappeared since then...
As for Bob Cobert's music being used or being adapted for the film, I could be forgetting a remark, but I only recall Pierson and places like ShadowGram saying that the main theme would appear in some form, not that any other Cobert compositions would be used. So in that sense it would seem that it hasn't been the intention to use Cobert's score but simply to adapt one piece of his music.
And as for the mansion at Beckenham Place Park, circumstantial evidence points more to its possible use as Windcliff. We know there's a Windcliff doctor in the cast of characters, so Windcliff figures into the story in some way. We've seen a video of an ambulance rehearsing its drive up to the building. And we've been told that a padded room set was constructed inside the building. Not that ambulances and padded rooms can't appear in some other location - but a place like Windcliff would appear to be more likely.
199 days 12 hours 1 minute 16 seconds until the day the Depp/Burton Dark Shadows is released(ET)!!
Less than 200 days to go!!