Forum:Double checking Battle phase rulings

I need to make sure of some rulings about the battle phase.

1. I heard from some source that there are certain cards that can't be chained in the Damage Step even though they are Spell Speed 2 cards (ex. Starlight Road). Can someone explain clearly as to why such cards can't be chained in these situations?

2. I'm a little confused as to how the substeps in the Damage Step are organized so I'll just present a mock situation. Ex1.
 * Say Player A controls a face-up Thunder King Rai-Oh.
 * Player B controls a face-up Defense position Gachi Gachi Gantetsu with 2 Xyz Materials.
 * Player A declares an attack with Rai-Oh, targeting Gachi.
 * Player A chains Book of Moon at the Damage Step, targeting Gachi.

Does Gachi get its destruction preventing Trigger effect? Does Gachi get its ATK/DEF boost? Why?

Ex2.
 * Player A controls a face-up Thunder King Rai-Oh.
 * Player B controls a face-up Defense position Gachi Gachi Gantetsu with 2 Xyz Materials.
 * Player A activates Book of Moon at his/her Main Phase, targeting Gachi. Gachi gets flipped down.
 * PLayer A attacks the "unknown" Set monster with Rai-Oh.

Does Gachi get its destruction preventing Trigger effect? Does Gachi get its ATK/DEF boost? Why?

For 2. I'm basically asking "At exactly what point of the Battle Phase do Trigger, Continuous and/or Quick effects apply?"

Thanks for the help.