when does your current visa expire? if it expires after you leave canada and before you get approved for an extension, then i doubt CBSA will let you back in as your visa is no longer valid. any implied status you have because of your extension and owp applications will end as soon as you leave canada i believe.
if your visa will still be current, then you are subject to examination at the border like any other visitor. if you tell them you have a pr application submitted and your visa is valid, there is generally no issue re-entering canada.
