Module 3 Right or Wrong?

Are the following sentences right or wrong? Correct them if needed.

1. Barajas is more busier than El Prat.
2. It's one of the most expensive shops in town.
3. May is slightly warmer than April.
4. I think Valencia is the third biggest city in Spain.
5. She is much more popular than her brother.
6. Is Benidorm more far north than Alicante?
7. His first novel was by far the better one he has written.
8. He has the same car that mine.
9. This film is completely different from the previous one.
10. The weather in Edinburgh is very similar to the weather in Glasgow.
11. You must to visit the castle; it's really impressive.
12. The museum is really worth to visit.
13. I wouldn't recommend to going in summer. I'd go in May.
14. Personally, I wouldn't buy one. They are too expensive.
15. How long should I stay there? One or two nights?