It's up to the reviewers to request that you be interviewed. Interviews are not very common and they would only happen where additional context is needed to make a decision. In my time on the committee, I never participated in an interview.
No. Generally speaking, all degrees are looked at identically. What matters are grades. I believe this is the case at every university except, allegedly, U of T (and I'm not even sure how U of T looks at this; I just don't believe that they would have a strong enough statistical sample to be able reasonably gauge grade inflation based on schools and majors vs. success in their law school).
There are countless discussions about this topic on the boards and you are welcome to search them to see people's thoughts. I don't want to get into that discussion in this thread and I won't entertain any more comments about it here. That said, I will say that it likely all averages out with a large enough sample size, so it really doesn't make sense that a law school would discriminate based on majors/schools like that in Canada. The US, on the other hand, has quite the varied field of educational institutions and corresponding majors, so some of that analysis may be necessary there. The quality of education in Canada at any post-secondary institution is quite good in general.
I don't know if other schools do it, but Osgoode does not (at least, not when I was on the committee, but I don't see why that would change).
The admissions office will know if you provisionally accepted but as far as I know this will not affect their decision. I certainly never took it into consideration. I don't even think that the committee members have this information readily available; they would have to ask the admissions officers for it.
J'ai vraiment aucune idée! C'est possible, mais normalement Mars et Avril sont les deux mois les plus occupés donc j'espère que pour toi tu sera capable d'avoir une réponse afin de prendre une décision!