Biggles,
Nothing extra is paid on top of utilities allowance. You get the 16075 per month and thats it.
Rough cost of water, electricity and cooling is about 1 dhs per sqf per month. So if your place is 2000 sqft in size, expect to pay 2000 dhs pm. This is averaged over the year. More in summer and less in winter. Also depends on how frugal you are but this would be an average.