First off make a list of all your major expenses.
Housing - you would probably need a 2br villa at minimum (I am assuming that there are 4 of you). The price of villas differs quite drastically depending on where you stay, try and find out where exactly you be working and the closest residential area. People do commute to work from cheaper residential areas, but depending on where exactly the two this can take hours of your day and elevate your blood pressure.
Depending on where you stay you will need a car and may need a second car for your wife.
Schooling for 2 children is not cheap - especially as they may be at different schools because of the age difference. When getting prices for schooling also consider the "hidden costs", fees normally exclude the following, books, transport, extramural activities, outings etc.
You don't mention whether your oldest child is male or female. If you have a son, unless they are specifically enrolled in a university in the UAE after their 21st birthday they can no longer be on your sponsorship (does not apply to female dependents).
Lastly, I couldn't help you with an estimate on salary, at present in the UAE there is no rail industry to speak of, besides possibly the metro system.
Sometimes the best thing to do is ask them what their are prepared to pay, as you are not familiar with the local cost of living expenses. Then add at least 30% to the figure and go back with a counter offer. All employers are going to try and get the best deal for themselves. If you get an offer then come back to me and I can help you put it context; it is very difficult without having enough detail to work with.