Someone I know interviewed with OmanAir a few months ago. He said that they are "very very slow" in processing your paperwork and are very laid back. So it is not unusual not get a response for a while. It is my understanding that while they are hiring they are in no big rush to have people on the property. Several Omani's I understand are leaving GulfAir to join and so I am sure they are getting processed first.
FlyDubai is only hiring Capts right now. If you are not a Capt on the NG they will not be interested in talking to you right now. In time they will
start looking at F/O's. In fact mainly even with Capts they want TRi/TRE's and people with training background. New hire Capts will fly from both seats when they first start up.