I am envious. That is a really nice clock.
The round thing is the pendulum weight. The funny looking rod (the long one) in the seventh picture is the pendulum. There should be a flat rectangular piece of brass with a rectangular hole up in the clock. It should be loose in there and will flop back and forth as you tip the clock side to side. The pendulum rod hooks onto that piece of rectangular brass. First you will need to assemble the pendulum weight to the rod. The rectangular piece of brass should fit in the center of the weight. There is that weird piece of wire curving around and ending at the center. The end of that wire holds the rectangular piece in firm. The thumb screw on the end of the pendulum weight is the fine adjustment in case the clock is running fast or slow.
The large key is for winding the clock. The left wind hole is to wind the clock (keeping time), the right hole is to wind up the chimes. If the chimes proves bothersome (too noisy at night), just dont wind them any more.
The small key is likely for something else. Dont throw it away. It will belong to something at your grandparents house. The extra piece of wire is a mystery. I would have to see the clock to determine if it belongs to it. It reminds me of a bellows rod (cuckoo clock).