For the crust, combine graham-cracker crumbs, cocoa, sugar and melted butter and mix very thoroughly. Line a clean, ungreased springform pan with the crumb mixture by pressing it first against the sides, then the bottom of the pan. (Crumb mixture should hold its shape; the sides will take about 2/3 of the mixture.) Press until very smooth and even all around. Refrigerate until chilled, at least 2 hours.
Melt chocolate chips in a double boiler and keep warm. In small glass dish or teacup, stir together instant coffee, water and vanilla and orange extracts. Set aside.
Heat oven to 350 degrees F. In a large bowl, beat eggs and sugar. Gradually add softened cream cheese, mixing well after each addition. Stir in melted chocolate, coffee mixture and the cocoa. Mix well. Gradually add sour cream, mixing well after each addition. Fold in melted butter and blend thoroughly but gently. Pour batter over chilled crust in pan. Place pan on heavy cookie sheet and bake 45 minutes. Cut off heat and open oven door, but do not move cheesecake. Let sit in turned-off oven 10 to 15 minutes.
Gently transfer cheesecake, still on the cookie sheet, to counter and cool to room temperature. Cover and refrigerate overnight. The next day, unfasten the ring from the springform pan and remove. If desired, garnish top of cheesecake with drizzle of melted dark chocolate, orange candy, chocolate-covered espresso beans and orange zest.