Amazing. Congratulations!!
1) Once you have PR. why would you need a work visa?
If you submit your passport now, and get it back in time, I assume they will have stamped it with a single-entry visa for landing purposes. Confirm this with IRCC by calling them.
2) If you ask for extension because you are getting married, they will revoke the PPR and ask you to submit further documents post-marriage, since that life-event alters your application. If that happens, you will have to re-enter on the work visa, submit passports after along with your spouse's.
Others, do chime in/correct.