I did the PRT in Jan. and again last week. Both times were the same:
Push-ups - straight form, no sagging, no ass in the air, and no stopping, arms have to break 90 degrees -just get down and push them out. They figure that if you stop you may as well be done.
Situps - More of a curl. Just grab your shirt collar or sleeves and stick your elbows far out as possible and touch any portion of the leg. Therefore, why I say more of a curl.
Run - get out there and bust ass, just be sure to not expend your energy too quick.
I did the prt in Jan but since I was at a CC my packet could not be sent out. Finally, after turning in 12 hours from UNC, I was allowed to submit my packet, so I re-did the PRT. Now I just have to wait.
Also, both times the officer was helpful. First time, it was a Senior Chief and he even ran the last lap w/ me.
Good luck.