Short answers, pulled from the story.
Forward contamination describes the transfer of life from Earth to another celestial body. It primarily focuses on microbial life and potentially invasive species that could be carried by spacecraft.
NASA made sterilization policies official with Management Manual NMI-4-4-1 on the 9th of September 1963. Prior to this manual all outgoing spacecraft required the same sterilization requirements regardless of target.
Ultramicrobacteria have been discovered as small as 0.2 micrometers across. This size justifies strict limits for biohazard containment facilities which must filter particles of 0.01 micrometers or larger.
The Apollo 13 mission included an anti-bacterial filter in the Lunar Module cabin relief valve from that point onward. This filter prevented contaminants from the cabin being released into the lunar environment during depressurization prior to EVA.
This future facility must be rated biohazard level four to contain unknown biohazards while preserving scientific value. It should double as a cleanroom and take seven to ten years from design to completion plus two additional years for staff training.