This is a publicity shot of Merry. You know the one, black and white pic with a black background.
I think this picture is from the Amon Hen part (sort of). The Fellowship is sitting by the fire and he walks up and says, "Where's Frodo?" It's that part, I think.
Ah, yes, my favorite part. The fireworks. In this pic, Merry is creeping around Gandalf's wagon.
This last picture...I have no idea where it is. Rivendell, maybe. It's a headshot, he's not wearing a cloak or a brooch, so...