Since a 996 has the same clutch as an SS, this is a fine place to ask

! No, you do not have to remove the push rod from the pressure plate, but it's not hard. Just whack it with a hammer and drift and it should pop right out of the pressure plate. Sometimes the bushing will stick to the end of the rod, but it can be persuaded to come off too. You may need to replace the bearing in the pressure plate (cheap and they don't last forever) and you'll definitely need to remove the pushrod for that. Don't know about the oil, but if there's not much, I wouldn't worry about it.