"Once per turn, during either player's turn, when a Spell Card or effect is activated on the field: You can negate that effect, and if you do, attach that card to this card as Xyz Material."

When it specifies "effect" does that include trap and monster effects? or is it just solely a spell card continuous effect?

Also,

"If a face-up Xyz Monster(s) you control is destroyed by battle or card effect: You can target 1 face-up Xyz Monster you control; it gains ATK equal to 1 of those destroyed monster's original ATK."

What if it's Hope Harbinger that is destroyed? Can his atk be applied another XYZ?

I think it's just Spell Card or Spell Card Effect.