Answer to Question 1
The presence of abundant ozone would probably be an indication of photosynthetic life because ozone is a form of oxygen, which is produced by life.
Answer to Question 2
Hubble's law describes motions due only to expansion of the universe. In reality we expect (and observe) that actual galaxies experience gravitational effects from other objects and galaxies they encounter, making their motions slightly different from the pure Hubble's law prediction.