Mostly questions about your aviation background and situations that you faced during your career and how you dealt with them.
Expect questions like:
- Why Qatar ?
- How are you going to deal with so many different cultures and habits ?
- Where do you see yourself in 5 years.
- (FO's) Tell me a situation when captain was going to make a wrong call and you had to change his mind. How did you do that ?
- Tell me a situation when you had to fly with someone who didn't want to follow company's procedures. What did you do ?
Etc etc...
Pretty straight forward, don't worry.
IF you would accept and advice, I recommend you making very clear that you always try to follow rules and procedures. I said that I would only deviate in case of an extreme emergency, where my life and the aircraft would be in risk.
One thing else, don't say bad things about your current/previous employer. It's not elegant and looks like they don't appreciate this kind of attitude.
Good luck !