Well...If I can answer that its:
1) Yes
Explanation: Prisma's Effect allows you to reveal one fusion monster in your extra deck and it can use the name of one of the fusion material monster of that fusion monster as long as you send that fusion material monster from your deck to the graveyard.
2) B. When you have no materials on it before the opponents attacks
Explanation: Number 39: Utopia would allow you to negate an opponents attack, but when it has no xyz material and is attacked, it is destroyed
3) Number 11: Big Eye's Effect is that, Once per turn:
You can detach 1 Xyz Material from this card to target 1 monster your opponent controls; take control of that target. This card cannot attack the turn you activate this effect.
Explanation: Big Eye allows you to take control of one monster your opponent controls. You get to keep that target until it is sent to the grave or removed from play, which takes it back to your opponents grave. However, when you use this effect Big Eye cannot attack. This can be a disadvantage sometimes, but MOST OF THE TIME it is an EXTREMELY AMAZING effect. This is simply because you can use that monster for many reasons such as:
Tributing the monster
Ritual summoning a monster
Using the monster to bring your opponents life points to zero ending the duel
XYZ SUMMONING
SYNCHRO SUMMONING
FUSION SUMMONING
ECT.
There are many uses for BIG EYE"S EFFECT.
So thank you for your co-operation