I actually have some water in my trunk from those sunroof drain tubes. I ordered new ones in case I can't clean out the old. Maybe I'll do a youtube video on how to remove and install that part.
I also have some mold on my stock seats as well. I'll let you know how I clean it but you have to get at the source of the water leak first.
In terms of interior, I would either leave it stock but install nice Recaro seats or do this...