1) Sam thinks that Australian people are nice and friendly.
2) Well, Sam have been in different cities in Australia, he flew to Sydney, he saw the Opera House and the bridge. He spent a day in the beach, watching surfers. He have been in Canberra, and then he flew to the Darwin, and there he ate crocdile meat and barbecue.
3) Sam liked this trip so much, it says in the last paragraph 3, 4 sentences.
4) No, Sam didnt have enough time to visit everything, it says in the last paragraph 2 sentence.