Thanks for this great information. So you’re saying that the parents who are getting PCC and medical request are close to get PR?Congratulations for the AOR!
Below are the answers to your questions:
when should I expect the PCC request? - It will depend on the visa office which will be assigned to your application.
Is there a medical examination request too? Yes a medical examination will be required too.
why don't they include PCC and upfront medical documents in the application form. - Because the medical condition and personal history could change at point, therefore IRCC asks for medical examination and PCC closer to the PR confirmation.