I am a PAF enthusiast and I don't wanna believe this but this happened to my bro, it was like 5-6 years ago, in his interview during ISSB, the interviewer just asked "Your father's name, which school did you go to" and and 2 or 3 more questions like this and said "you can go now", he said it...
my friend passed the medical tests,its same as mentioned by Xeric,check this here:
http://www.defence.pk/forums/join-pakistan-army/207587-preliminary-final-medical-exam-pak-army.html
No,for commision as an officer you must have done A levels,eligibility criteria is:Senior Cambridge in five subjects and should have passed Physics and Math’s or Biology in “A” Level.
Check this thread for info about medical examination
http://www.defence.pk/forums/showthread.php?p=3406890
And yes,it's good to have a personal checkup.
if you have passed A level's first year according to the desired requirements,then you can apply with "Hope Certificate"
And AFAIk registration for TCC have already been closed.Wait for the next one
Registration for PMA long course 132 is starting by 8th april,2013.
Interested candidates visit their nearest AR&SC or register online.
P.S: Due to my post count,I am not able to post links.