New build progress, second floor frames up. #buildstr

New build progress, second floor frames up. #buildstr

So many questions,
What is the piling/retaining wall in the right?
Why the pink hue to the second floor lumber? Treated?
The retaining wall retains the 5 car parks. it's a steep site so you come in from the parking above the house. The pink is untreated internal timber. The builders spent all day straightening the frames today.
Very tidy looking framing!