So do you suggest not bringing it up with my department and just wait and see?
No, I am just giving a possible source of the delay. If you are planning to start work there in a couple of months and still do not know what is happening w/r to your spouse, I do think you should talk to someone.
Does P&T committee comprise of faculty from the same school or different schools in the univ.?
This is institution-specific.
Do you know of cases where P&T decided against the Chair's and Dean's interest?
Oh my, yes. In both directions.
Incidentally, one issue with spousal hires is that departments don't like to have faculty thrust upon them, especially if there is a mismatch between the candidate's specialty and the departments strategic goals. I hope the Chair in this case is reflecting the will of his department. - DvF