(a) housing in the GCC including Doha is rising as we speak - get your employer to commit to a certain standard and that they will pick up the tab - 3 bedroom villa at least 2 baths and furnishings OR a furniture allowance of at least QAR30,000 in a new build (things deteriorate rapidly in 40C+ conditions - the employer is responsible for this housing NOT YOU.
(b) annual tickets (or cash in lieu) home (to your point of origin in Canada) for married couples plus up to 3 dependents (children), standard for this area in your income bracket
(c) medical covered for everyone again, standard
(d) education allowanace (typically QAR25000 per annum per child up to 3 children) this may be negotiable either upwards or downwards

You may be willing to compromise on any or all of these points - but these are the areas where you need to consider if it is worth it to you to come here.