Although I am not in Montreal and I currently live on Ontario, one thing that I know for sure is that you will need to sign a 1 year long lease. This rule is applicable all across Canada. There is no concept of lease breakage as such - which means if you need to move before your lease completes, you will have to find another tenant to "sub-let" the apartment for the remaining period of your lease. However, depending on the management company of the property, they may have some exceptions included, like moving because of the job etc. But I would suggest you clearly understand all the leasing rules form the apartment management you are planning to rent from.
Secondly, they will need to see some proof of income in order to approve your application for lease. A letter from your employer stating your salary and employment details should be good enough for that. Proof of income from any one of the applicants should be sufficient. They are basically trying to make sure that you will be able to pay the rent every month.
Thirdly, there is a background check involved that all the property management companies would do before approving your application.
Finally, there are application fees involved (per applicant, i.e. you and your spouse will be two applicants for this purpose). These are usually non-refundable.
