1. How much would it cost annually for a grade-1 student in any indian school?
Its feasible. not sure of the amount...

2. How much would it cost for 2nd hand car (2008+ model civic or corrolla)?
Qr : 40,000 +

3. What is the fuel cost per gallon in Qatar?
1 litre = 1 riyal Super

4. Which location would you suggest for staying (I am looking for a place where there is a School,Hospital, Grocery and Shopping mall that Indian Communities normally prefer) within 10-15km from city.

The area you are expecting can be Gharafa, Old Airport, but school is not very close + Qatar Traffic is bad.

5. How much would be average monthly rent for an Indian family (2BHK or 1BHK) within 10-15km from city?
2 BHK - QR: 7000, if you want in a good location
1 BHK - can be varied from 1800 - 4000.