The effect that destroys Spell/Trap Cards does not target.
The effect that adds 1 "HERO" monster from your Deck to your hand or destroys Spell/Trap Cards can be activated even if this card is Special Summoned during the Damage Step.
If "Elemental Hero Stratos" is Summoned while "Thunder King Rai-Oh" is face-up on the field, then you cannot choose to activate the effect which adds a "HERO" monster from your Deck to your hand. However, you can choose to activate the effect which destroys Spell/Trap Cards.
These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
↑Konami Judge Program Rulings are considered unverified, as their source(s) are not publicly viewable. They are not confirmed as applicable to the TCG until they have been officially published by Konami.