You should apply it less than 4 months prior to expiration. If you apply after expiration, you need to apply along with a status restoration. It is most likely that BOWP can’t be done at border or outside of Canada. I am not 100% sure.
Usually MP office will send a consent form to have your consent of access to your application. You need to fill out the form with your application info
You are free to try, but usually you will only receive an automatic reply if your application is not having a final decision. Actually, to call the hotline would be helpful to know what stage your case is in.