I would recommend talking to students at the school you are interested in to ask them what scores they and their classmates were accepted with. As Stevie said, you can also check the school's average admission scores.
@lianaf92 I do not know much about OLSAS, but make sure to post your question on lawstudents.ca If you have not done it already. It is a very helpful community like 7Sage but more focused on admission to Canadian law schools.
Check the box, it's really just used for statistical purposes after admission decision has been made. A few schools I've applied to had the responses to that section hidden from the actual PDF application being sent for the adcom to review.
Most of mine have written a few law school recommendations, so, they knew what to do. For the others, I asked that they address it to "admission committee."
... . Note to applicants applying for admission on examination: do not include ... part of an application for admission (see 22 NYCRR 520.12 ... his or her application for admission questionnaire.