The article you linked to already contains the answer you are asking for:
x64-based versions of Windows Server 2003 that are running on a computer that uses a multicore processor or a hyper-threading processor support a maximum number of 64 logical processors.
As to your second question, I would guess that Windows 2003 will detect up to 64 physical processors and any number of logical processors, but will not use any logical processors above the maximum of 64. In any case, I don't see that it makes much difference whether or not it detects the additional processors if it isn't going to use them anyway!