I've always used "Dark Savant" to get past Milano Calzone when he asks "what or who" are you looking for.He will then lead you to Don Barlone who will give you some important info regarding the A.D.
One of the rooms in this area will have a key sitting on a table/stump. This is the Ratt key that will get you into the "Breeder Rats" room.
Be well prepared for the fight with the Breeders and Rattkin Archers.
For questions 2 and 3. You won't be able to open either one at this time. You'll have to leave Trynton to get what you need to gain access to those areas.
Spence