Re: Crew survivability
The astronauts did wear full pressure suits for the first few launches because they had ejection seats. Those were removed after the 3rd or 4th flight. After that and up through the Challenger mission, they launched and reentered wearing a flight suit and helmet as shown in the picture of Christa McAuliffe during training.
Following Challenger, they went back to wearing pressure suits. They needed them to safely bail out in an emergency.