Being from Morocco, I think you have a standard living style that you would like to maintain.

It also depends where you grew up... but lets assume a mid-style life pattern.

You can find a decent 1 bedroom apartment in some old areas or distant areas (about 10km from center of Doha) for around 4,500-5,000 QR/month. If you search well, you will find better prices. Look in the adds and have a tour...

For a car, If you plan to stay for 3 or more years, you can get a bank loan and buy a car and pay around 900QR/month for a small car (Nissan-Tiida).
If you rent it, it will be around 1500 QR/month.

Living costs for both of you per month is around 2,500-3,000 QR.
Going out to regular quick meal restaurants twice a week for one month would cost around 600-800 QR.

Add around 500 QR for bills and another 250 for phone, this would make a total of around 10,000 - 11,000 QR/month.

I would say if you work things well you can save around 5,000 QR/month.

If you are a big spender and like high life style living, then forget it...