Answer to Question 1
TRUE
Answer to Question 2
They all come from explosions of white dwarfs that reach the white-dwarf limit, so we expect them all to have the same luminosity; observations of white-dwarf supernovae for which we can measure distance independently confirm that they all have the same luminosity. Since we can assume we know their luminosity, we can use their apparent brightnesses to determine distance from the luminosity-distance formula.