Trying to practice the idiomes

Hi there! I'm studying some new idiomes. To learn them better I've composed a sentence with each of thexe expressions. Please, have a look at them and correct me if I used them in the wrong context. Thank you!

1. Our car had broken down on the way to the airport, but it was really a blessing in disguise. Scrolling the news while waiting for a car-service tow truck we found out that the plain crashed in the air.

2. They promised the moon to the people who bought the company's stock! But the firm went belly up soon. (by the way, "to go belly up" - is it a slang, or just informal?)

3. - Have you known that Mary's got married?
-I couldn't care less. After what she did she's not my friend anymore.

4. All the tickets were sold out in an hour. Everyone and his brother wanted to see the performance.

5. He always has such a foxy expression on his face, that when I speak to him I can't help feeling he's pulling my leg!

6. - Did you know that our famous morality activist Kate was blamed for drug dealing?
- No way, no way!

7. -How are you?
- I'm under the water after my holiday marathone to bars.

I have a couple of points to add to the others.  'Belly up' is slang and is used quite often in British English. 

7.  I'm under the WEATHER  after my holiday marathon VISITING BARS.  (Do you mean you went to a lot of bars to drink alcohol?)