I did the heater motor replacement a few days ago and I also discovered soaking carpet so I'll follow this with interest.
I was short of time and only had a chance to do a quick check on the scuttle drains that looked OK also. Wife is away in car for a week so I won't get a another chance to look properly until weekend.
I'll certainly look at the sunroof and that A pillar pipe.
Also found a useful video on Youtube that's worth a look.
https://www.youtube.com/watch?v=rzpaJ4ulRic
On a side note. How did you get on with doing the heater motor? I found it very difficult (actually impossible) to get the new motor/housing back in to the car. I ended up taking a hacksaw to the bottom of the glovebox aperture. It went straight in then. I'm pretty sure that's not the right way
