I am EXACTLY in the same situation as you: CoPR issued before March 18, expired on August 1st, never contacted IRCC after it expired, only before it mentioning I would not make it and receiving, as answer, that it should be fine and I would have to raise a new web form to ask permission when I'm ready. Never raised and by now, according to IRCC's website info, I shouldn't, since we are since December 23rd supposed to wait to be contacted instead of contacting them ourselves through web form. So now I'm just waiting...
Regarding the re-medicals... Are you sure you are going to need it? Why don't you wait until they ask you? If you are sure you are going to need it and want to get ahead, then make sure the place you do it has the proper connection to IRCC. If so, you should be fine, if you read above, in this thread, I'm pretty sure someone did this before, that is, sent a re-medical exam without being asked, and it went well.