Mostly, the embassy just wants prove of first year tuition plus living expenses and continuous means to pay remaining amount till graduation. Proving that is subjective to each application and any slight problem in that regard can lead to a refusal in application
Depends on individual preferences. If you’re overwhelmed with the application and want to avoid any further inconvenience ; an authorized Expert would be the best option in your scenario. But if you can go to the Canadian website , read from other forums on previous successful applications and do your research extensively; there’s no need for an expert as the whole progress is simple and self guided