If you are asking if it's ok to start the spousal sponsorship PR application process with the passport close to the expiry date - then yes. You must however have new passport ready before your application is processed and, if granted, passport request arrives. Better have it replaced ASAP, don't wait until the last moment.
Sorry, didn't get the second part. You want to do upfront medical for the application? I believe it is explicitly said not to for this type of application.