UTH only heats the floor, it does very little to nothing for ambient temps. And yes make sure the UTHs, both of them are controlled by a T-stat and remember to take the temp readings from the glass under the substrate in case your ball burrows down or pushes the substrate aside.

As for feeding, my little pied girl took a rat after 2 days and since then till now, she pretty much eats anything and gets fed every 3-4 days but now I'm pushing her out to 1 week as she went from 102g to 386g in about 2 months.

Each snake has their own likings. My girl never uses her cold side except to poop on or sometimes play around in but come day time or sleep time, she always goes back to her hot side hide.