1. Yes there is a night life. No problem there.
2. Lots of singles (especially men, the ratio is about 7 men per every 1 female). Be aware that the men tend to be aggressive here. I guess it's because of the competition for the girls.
3. Cabs are not that acccessible. They are around, but at peak times are not available unless you have booked 24 hours in advance. Not that expensive, but if it is to be your main form of transportation, it will add up. An alternative is to look into hiring a driver. These are very common here. They are available on a full time basis (around 2000QR a month) or a part-time basis.