Never EVER ask about the number of Leaves for the exam, working hours.
You can ask about the variety of Audits.
If you will ask about leaves, working hours in the interview only, then this will be your biggest mistake.
First Join. Do hardwork. Impress the partner. Then, ask for Leaves.
After joining, your peers in the firm will tell you the reality of No. of Leaves and Working Hours.
Now coming to Questions, ask following questions and you will be hired ( Hopefully)
1. Ask how the professional development of articles and continued learning processes work at the firm level.
2. How do you evaluate performance of an article.
3. Ask about the office culture.
4. What is the financial health of this firm? Ask this question. There is nothing wrong in this. This will prove that you see a future in this firm. This will show your maturity.
I asked my CA, What is your gross annual revenue ? he smiled and gave me the answer. After hiring, he told me that none of the articles in his life has asked him about the Income. He liked my bold approach. I asked him if this was rude. He replied, there is nothing rude in this. All the employees have a right to know about the total revenue of the firm.