Any suggestion for our team
The best places to start a fast food stall or a restaurant would be near offices, coaching classes and colleges. This is because generally students and workers look for good budget options to eat when they are hungry. So if the pricing of your food is not too high then these two are the best places since students do not carry a lot of cash most of the times. Also if you are looking to set up a stall in an area which already has many such food stalls present then you will have to serve something different and the quality will have to better than all those other places, else your venture may not be profitable.
Being a total hogger as well as a student I would like to suggest the following places to you.
Marine drive: There are many good restaurants near marine drive but they are expensive. There are no budget fast food places right at marine drive. Since it is frequented by a lot of people everyday, you can consider it as a possible location.
Fort: Cst and churchgate have a lot of offices as well as colleges. The workers and students swarm these fast food joints during lunch breaks and post work and college hours. There are too many stalls already but you will always find a good spot.
Markets: there are a few places in Mumbai which are famous for shopping. These are bhuleshwar, Crawford market, colaba causeway, hill road and so on. Generally people who come to shop at these places prefer to relax by eating some good food before they start another round of shopping.
Borivali and Kandivali West: I have seen a lot of good places like Di Bella and The Chocolate Heaven also opening up in Borivali and areas in Kandivali like Mahavir Nagar. Most of the population is Gujarati and they have a penchant for good food. Your math can hardly go wrong here unless you serve bad quality food.
Famous college clusters: If you see then there are few trusts which have 3-4 colleges located next to each other. Mithibai and national college are two such examples. Being a student of TSEC which belongs to the same board as R.D. National, I can assure you that if you open up a dosa or a chat stall next to my college, you shall earn more than enough.
So these are a few places which I think should be good. But these aren't the only ones. You could look for more such similar localities as I described and you should be good to go.