Dear,
If you are talking about Re-Police Certificate request from Canadian High Commission Islamabad and you want to get it from Kabul then the procedure is that Once you get Police Certificate from Ministry of Interior Kabul, then you need to take it to Ministry of Foreign Affairs and they will fax it to Afghanistan Embassy Islamabad and will provide you a FAX number through which you can collect it from the Afghan Embassy in Islamabad,
For medical test they take URINE and BLOOD Samples and perform different type of tests like HIV, Tuberculosis, Hepatitis ETC ETC, they also take Chest X-Ray,
Regarding waiver of interview if you get RE-MED request from Canadian High Commission Islamabad, then most probably your interview has been waived or you can order GCMS notes to see if you can find out a part where it mentions that Interview is Waived, there is not other way to find out about it,
God Bless and Good Luck!