Answer:

2. When a pendulum bob is pulled back and released from rest, the force of gravity does positive work on the bob as it swings down. After the bob goes through the low point, it swings back up, and during that upswing, the force of gravity does negative work, bringing it to rest at the top of the swing.

3. The swing continues moving back and forth without any extra outside help until friction (between the air and the swing and between the chains and the attachment points) Slows it down and eventually stops it.