As for the house they'll use as Collinwood - I think I miight actually be anticipating learning that news more than I am learning who'll be cast in the remaining roles.
What are you hoping for, exactly? Historical accuracy? I'm not sure WHAT a rich man's house would have looked like in 1790's Maine
but I'm pretty sure it wouldn't have looked anything like the one used for the original series.
Of course, there's always Second Empire....the quintisential "haunted house"....mansard roofs and French doors. That's MY favorite style of house and I'd love to see it....but it certainly wouldn't be correct for the time Collinwood was built.
I don't suppose they'll be sending crews to Ohio, alas...
There's a superb view here that might be reminiscent of the Collinwood pic above...
I love MB's idea of an ancient house being re-built. The old houses I have seen here in Maine are simple colonials with clapboards and shutters(very no frills in keeping with its puritan roots) Architecture in Maine didn't get interesting until the Victorian era.