the cloudiness is probably due to your sand being stirred up by your wavemaker, please check that.
You tank water smells because of the ammonia from the market prawn, and please leave the dead prawn alone, it will decompose altogether by 2 weeks time.
you better start reading the forum (especially the stickies) and other website more to learn more about marine tank keeping.
unless u have been dosing bacteria, I doubt you will have any bacteria bloom to cause cloudy water. assuming this, your cycling should be completed in 3 - 4 weeks.
Leave your skimmer on, you may not get any dark skim mate due to no nutrients in your water column.
Please make sure the ANN cycle is completed, get some reliable test kits like Salifert brand. Test for NO2 (make sure this is zero) and NO3 (should be high > 20ppm), when this trend is noticed, your tank is fully cycled.