Additionally, I don't know the answer to your second question - if Canada does a background check on you (which it does) and Bangladesh reports that you had a conviction for dangerous driving, then they will know, and if you did not declare this on any visa application, then you will have an issue.
So really, the issue is whether or your PCC will be accurate. You've said you're obtaining it properly, and the record is not on your PCC. In that case, a background check should not show it either. However, if there is, in any way, something you're doing that would remove the conviction from a PCC but the conviction would still appear in a background check, then you will have an issue.