1) The document discusses reasons for editing digital audio, including eliminating background sounds, trimming audio to fit time constraints, and changing meanings by editing words.
2) It describes using Adobe Audition software to edit audio tracks by adjusting volume levels, working with multiple layered tracks, and removing unwanted sounds like coughs.
3) Techniques like cutting, joining, fading and removing beginnings/ends of audio are discussed. Matching audio to video using clapperboards and adding dialogue in post-production (ADR) is also covered.