I am assuming that you are going to apply to both Canadian, and American medical schools. I cannot give you reliable information regarding American medical schools, as I didn't apply to any. However, the "standard" number of schools that I hear about through other websites and web-forums seems to be between 10-25. This is assuming an average applicant. I don't really think that there is such a thing, but I'd assume that student should minimally have a GPA in the B+ to A- range, with at least an undergraduate degree, an MCAT of 27 or higher, some clinical volunteer experience, solid letters of recommendation, and a good command of English. Some research experience also helps, particularly if you managed to get your name published.
In Canada, I think you should apply to every medical school that will let you apply, and that you believe you would attend if it was the only school that accepted you. I don't believe that there is a great deal of disparity in the quality of education among the Canadian medical schools.
All of the Canadian schools are heavily subsidized by the Canadian government, with the purpose of producing doctors who will remain in Canada to serve the public. As a result, I believe that all the schools receive decent (even in these times) funding, and have the capability to hire first-rate professors and clinicians. As an example, I've found very few "bad" lecturers at UBC. Most seem very dedicated to their work, and have a sincere interest in your learning.
Applying to medical schools isn't cheap. Not getting in on your first attempt because you applied to too few schools is even more expensive, since that's the equivalent of losing a year of a doctor's salary. If you believe that medicine is what you want to do, and you have a realistic chance of being accepted, I'd apply to every school that I thought I would potentially attend.
To answer your final question, UBC selects a majority of its entering class from people who are classed as BC residents. In fact, in my class, there are no people who are out-of-province. I have more statistics on UBC in my website.