Certainly possible - but it needs to make sense in context.
For example, you have been working in a corporate job for the past 10 years and now you want to do an MBA (from a good school) to move up the corporate ranks. That makes sense. Lots of people in business school are in their 30s and are coming back to school after a long gap.
It's typically not 15 years, but it is possible. One guy in my B-school class was 57! His company wanted to elevate him to a C-level job and for one reason or another they wanted him to have an MBA, so they sent him to b-school. It was pretty awesome having him in class, he really knew his stuff.
If the study doesn't make sense in light of your previous work/academic experience, you will find it difficult to get a study permit. If your primary intention is to immigrate, that will be pretty obvious.
Yes, if you get a study permit, your wife can apply for a visa to accompany you. Getting it is not guaranteed, but certainly possible.
