Hi... hope this gives you an idea.

First, It would be best if you clarify with your company if your getting FAMILY accommodation or housing allowance.Rent either in Doha or al khor is a little bit costly. QR 3000 as you mentioned would only mean 1 room with attached bathroom in a portion of a villa. Do the numbers on how much a villa or flat would cost.

Rent policies is usually 1 month advance & 1 month deposit.

Second, it is advised to stay near working place. Doha to Al Khor distance wise is 1-2 hour drive(excluding traffic in Doha city. You can always roam around in Doha on a weekends.

Third, Cash is very important but you do have options to get money through machines.

Lastly, It would be best to get pre arranged services on transportation & hotel. Roaming around Doha with a map and a excited family would be a little bit tricky.

Good luck!!!