Dealer: South, Vul: E/W [hv=pc=n&s=saq8hkj96d752ck42&w=sk952hqt4dj3cqt63&n=sj64ha73dt94caj95&e=st73h852dakq86c87]399|300[/hv] What is North's best response to 1C opening? If North responded with 1NT, should East come in showing his excellent Diamonds? If bidding went 1C-P-1NT-2D, what should S/N next?