Okay Air Won, this how it normally goes for what you, in America, call touring. If you work 6/6 for example, you may or may not get some days off, depends on the company. For the pay, with Gulf Helicopters you are paid a daily rate of $X per day on site either in Qatar or wherever they send you to work (whether you work or not), but you're not paid for the time you're on leave. so, for Gulf, on 6/6 you get $X x 183 per year. It does mean that your pay goes up and down. For ADA they also actually work on daily rate, but they just basically say that 6/6 is $X per year and 8/4 is $Y per year and then pay you one twelfth of that per month. It doesn't quite work out like that, but in general that's about it.
Hope that helps