More rulings from the JERP.
If you can't discard at least one card to pay SSpell's cost, you can't activate it.
SSpell must be chained to the magic card it affects. So if your opponent chains that magic card, you can't.
If a normal spell card has a choice between two effects and SSpell copies its effect, it uses the same effect as the original.
If Pot of Greed is copied by SSpell, your opponent can't chain Spirit Mirror to SSpell, because SSpell's effect doesn't target the player unlike Pot of Greed. (Spirit Mirror is a trap that can switch the target of a card that targets a player)
If SSpell copies Swords of Revealing Light, or DD Capsule, it gets the initial effect, but unlike the card it copies it does not stay on the field.
You can fuse two sets of monsters by copying Polymerization with SSpell, but if you only have one set, SSpell's effect will fuse it and Polymerization will resolve without effect.
If you copy Metamorphosis, you cannot summon a monster by SSpell as you did not sacrifice a monster for it.
Edit: Disclaimer, some rulings MAY change. It's still a new card.