A) To my knowledge and research this picture has been circulating around the Internet for sometime. It either is part of a Video Game (one person told me the game is called 'Just Cause 2'), or it's an artist conception of something he likes, or it may be some type of prototype weapon. But the answer is NO it does not exist as a real weapon.
First of all non military and police personnel (civilians) cannot own a grenade launcher without obtaining a Class III Stamp. Also military and police don't buy fancy outfits such as the grips on the picture shown below.
If someone can tell me who makes this as a real weapon (handgun with grenade launcher), please let me know. Just because something circulates on the Internet doesn't mean it is real or if it is, that it's available for sale to the public.