1.I don't like playing cards*
2.Kate agreed to come
3.The goal helped (us?) to win
4.They are afraid of swimming in the sea
5. Sam thinks of being a pop star
6. I want to sing
7. They decided to return home.
*When the gerund is used it means I generally don’t like playing cards.
The infinitive would be used for a particular occasion. eg I shouldn’t like to
play this game