2) If you say X or N must be very large, does this prove that you measure torture and fun using in effect different scales, and therefore are a deontologist rather than a utilitarian?

Not in and of itself. That proof would also require knowing that this deviates from the actual utility assigned to each state. Without knowing those numbers you can only draw inferences that they are probably deontologists based on estimating the implausibility of the implied utility evaluations.

Mind you, the vast majority of people claiming to be utilitarian do seem to be deontologists, regardless of their verbal expressions to the contrary.