These days security at all the airports in India is very strict. You will have to undergo several formalities at the airport itself. Immigration check is a must for all the passengers be it Indian or foreigners and that too both at the time of arrival and departure.
All the passengers who are travelling from other countries will have to fill in an arrival card which is necessary for custom clearance and in the same way you will have to fill the departure card at the time of flying out of India.
All the major international airports of India try their level best to ensure that the experience of all the passengers who are arriving or leaving the country is pleasant. For the convenience of passengers the number of immigration desks have also been increased so that they have ample time for other formalities at the airport. The official language spoken by all the officials at the Indian airports is English.
When the immigration officer conducts the check on your passport, you should ensure that your passport has the arrival stamp, also when you are leaving the country make sure that your passport is stamped before you leave the immigration counter in order to avoid problems at a later stage.
In India sometimes your luggage can be scanned, if you experience such a situation, do not panic, this is common practice at all International airports in India.
Generally the luggage carts are available to all the passengers free of cost, but sometimes you might get unlucky and do not find any carts at the baggage pick up area, this happens because of the large volume of passengers, just be patient and wait till someone from the airport authority gets the carts back from outside the airport.
You can also very conveniently exchange the currencies at the airport itself, the currency exchange counters can be found inside the terminals. Make sure that the receipt is kept safe with you.
You need to be patient when flying in or out of India, it is a unique experience for expats and there is no point in getting frustrated or stressed about it.
Pro Tip: Try to reach the airport at least 3 hours before an international flight. Leave your house or hotel keeping in mind the traffic especially in the major metros like New Delhi and Mumbai.