Instead of carrying Indian Rupees, Buy USD in your home country, and carry it instead.
It will be much easier and acceptable here for exchanging USD to QAR in Qatar.
You can use USD to buy anything at the airport, remaining money will be returned to you in QAR.
Is your company providing you Airport Taxi Pickup?How will you be going to your accomodation from Airport?
Do you know the contact No of the company personell?
Once at doha airport buy a calling card or check if you can by local SIM card ( 25 to 50 QAR) with your passport.

Cost of living here depends on your lifestyle, varies from 800 QAR to 2000 QAR.