An ETF for your undersatnding is a mutual fund that trades on the exchange. This should give you a basic idea:
Of course they do but they are cheaper than equivalent mutual funds.
It depends on the duration of a trade. If you want to express a short-term view or do tactical trading, then ETFs make more sense than index funds because they don’t have any exit loads. You can get in and out of an ETF just like you would a stock.
Having said that, not all ETFs are liquid in India and these are still early days for ETFs in India.