Student Visa/Immigration Question

Hi,

My boyfriend and I have been together for 4 years and we have finally managed to get things sorted financially for him to move to Canada at the end of the year. He is from Mexico but currently working for an American cruise ship company to save money and I am a Canadian Citizen with a full-time job. Our plan is for him to arrive here on a student visa as we're not quite ready to get married yet and he would like to make his start here by going to school.

If he moves here and during his studies we decide to get married, we would like to then apply for me to sponsor him for permanent residence. Is this possible while he is on a student visa? If we do this, will his student visa be null and void? Will he still be able to pursue his studies? How does this work? There is also a chance that he would like to extend his studies as his program has a graduate portion; however, this would mean in the normal circumstance that he would need to apply to extend his student visa. How would this work if we have an application for permanent residence?

Any help or advice you could provide me would be of great help!
Thank you!