Drinking- No issue as you are probably just missing it. Like stated above though much of their water is had with their meal.

Prey- Pinks are much to small. Feed prey that is near the same size as the snakes thickest part of its body.

Humidity- It appears to be staying low. The best tip and trick for those with a glass tank is to add damp moss to the hides. While you are having stuck shed or poor sheds keep the moss moist. After you get a nice full shed you can start to allow the moss to dry out before making it moist again. Then at the first signs of a coming shed keep it moist again until the shed is complete at which time you can go back to allowing it to dry out.

What this does is creates a higher humidity zone within the hides. The tank is still going to show low humidity but the snake will be getting what it needs from the hides since that is where they stay most of the time.