Answer to your questions:
1. Cost of rent for 1/2 BR Appt in area near C- Ring road........ QRs.4000/- to 6000/- per month.

2. Convertion of UAE Driving license to Qatar license...........Can not get it converted unless you have a residence permit in Qatar.. You need a NOC from your Qatari sponsor... however, you can drive here with a valid UAE Driving Licence.

3. Traffic situation in peak hours ......... not much.

4. Other important costs if different than UAE............ allmost same.. not much difference here.