Is it important to have good command over the English language in order to qualify IAS exam?

You don't normally employ English orally. But, for running the administration, it is necessary to have a command over English. You will find its need more in some parts of India.

Yes, it is important to have a good command over English to give an IAS exam. Your English skills are tested at all the levels: written, GD & PI. It is very difficult to crack this exam. If you are sure that you want to become an IAS, then go for BA in public policy and administration course from UP

Yes, definitely especially during the interview session and essay writing. You must be good in English to score good marks in these subjects. But there is a facility of attempting Mains exam and interview in your mother tongue but that is secondary. The prelims exam will completely be in English onl