Wow, congratulations! So, your ghost was indeed for the final review. I still wonder if you were under SS at all or not? If you were, how long it too.
Anyways, I am very glad to hear that you got your ppr and I am sure it brings a ray of hope for all who are waiting.
About landing, the policy is either use it or lose it. However, given that you are an out land applicant, they have probably extended your medical for another year so you have enough time for landing. To make sure of what to do, raise a CSE. They respond precisely for questions like these.
Are you currently living in the US? Do you have single or multiple visa? So, in case you travel out for landing, would you be able to go back? If so, I don't think you need to worry that much. you can go land and go back live in the States for now.
Congratulation, Your medical approval date and extension should be indicated in your file, you can call CIC to make sure about extension also, they extended my medical and it showed in my online profile.