As mentioned previously, it is a case by case situation. When I left I had nothign, no house, no wife, no kids, I was a basically a bachelor with an oppportunity. So when I left I had dad's accountant look at the situation and help me out. He said that bacially if a guy sold the house and the cars, took the kids out of school, cancelled medicare, drivers leicense etc for the entire family, then it would be pretty obvious that the family was leaving. But in my case, as I did not have any of that, we just had to be careful that we did not forget anythgin and follow up on the case. In the end, I cancelled all that I had such as bank accounts, credit cards, drivers license, medicare (all of which are mandatory by the way) and sold the car, and my case was 'approved' with no complications.
As for the people that spend a significant time outisde of the country, you can qualify for a redustion in income tax, but you have to be outside of the country for 6 months plus a day i.e. 183 days. Thats easiy enought o prove as everytime you leave and come back you passport gets stamped, but the thing here is that the governments view on this is that a person HAS TO BE a resident somewhere. So if you dont make yourself a resident somewhere other then Canada, then Canada presumes you are still a Canadian resident and will tax you accordingly.
My suggestion is that if the young lady in question is only going to be outisde of Canada short period of time then it might not be worth the hassle to go through the process of cancelling everythign she would need to cancel to become a non resident just to have to re-apply a short time there after. However if this will be an extended tiem away or every if it MIGHT become an extended period away then definately go through the process and make herself a non-resident.
As for the tax agreement that Canada has with the UAE, it is current at 25%. This does not effect your income, as far as I am awre, rather it's for investments that you may still have in Canada. For example I recently closed my RRSP account and had to pay 25% tax on the amount.
As for property, I would suggest you seek proffessional advise as it really depends what the property is used for which will determine whether or not you will exposed to taxes or not.
Good Luck, I hope it helped.