I was on a student visa too. It actually expires on July 31, 2019.
I applied on January 27 for my PR + OWP.
And I continued working with my company. I quit my program before the last semester.
You don’t need to apply for a visitor visa because you’re on an implied status the day you put your application in.
As i know you applied for PR and OWP before your study permit expired. However, you are not allowed to work while you are waiting for your OWP and your study permit is expired. Just only the PGWP is allowed you to work when you are waiting for your PGWP and your study permit is expired.