IHS actually is an abbreviation for In Hoc Signo, which is an abbreviation of the words In this sign (the cross) we conquer. Maybe Obama wanted the hammer and sickle, or his familiar colorful balls on the wall over or under the IHS, and the compromise was to remove the IHS since the alternative would have been a little too much for even the Jesuits to sell to the faithful, or even to the usually tractable and generally apologetic catholic backsliders whose faithful Catholic mothers are still alive.
Not in this case.
No; it's an abbreviation of the Holy Name in Greek letters. Already dealt with on this thread.