Lesson done!
here are the answers.Be sure to double check your work and If I made a mistake then sorry.Here are the answers.Any mistakes then PM me or post below.I will use Devilmans answers since they are very detailed..
1: No. Sangan activates in the graveyard. Angel07 still negates any and all effect activations, regardless where.
2: No, Widespread Ruin does not target because that requires the player to choose a single monster to consider it a target. Although one monster, you cannot "decide" which monster on your opponent's side of the field has the highest ATK, so like Fissure and Smashing Ground, it does NOT target.
3: Damage Step/Sub-step 6 of a battle is when Jujitsu activates. Damage calculation happens before, so DD Warrior would remove himself and Jujitsu BEFORE Jujitsu's effect resolves, and because he's removed, Jujitsu's effect fizzles and does nothing.
4: You may only use Il Blud's effect if you revive it with Monster Reborn and then GEMINI summon it. Gemini monsters are normal monsters until gemini summoned, and they are normal monsters in the grave, so you would need to ensure Il Blud has his effect first, otherwise he's just a normal monster.
5: Yes. A cost is payed before any further action is taken, and you never get a "refund" for a cost. Costs are mandatory, and in the case of two Solemns, both player's LP would be cut in half.
6: In the Battle Phase itself, yes. Yes you can.
7: Necrovalley, although a picky card with a lot of rulings has one key ruling. It does not affect the effects of monsters who activate their effects when SENT to the grave or that activate in the grave such as recruiters, or in this case Treeborn Frog, so you should have no conflict bringing the Frog back as long as the Necrovalley isn't yours and you have no Spells/Traps on your side of the field.
8: Once Necrovalley hits the field, any monster afterwards is not removed, but any monsters prior stay removed because Necrovalley forbids any and all cards to be removed, so instead the monsters would head to the graveyard.
9: Crush Card requires a monster with 1000 or less attack. Does not ask for ORIGINAL attack, so yes... Shrinking a monster with 1001-2000 ATK would allow you to target that monster for Crush Card Virus.
10: Jinzo's card mentions negating face-up traps... So yes, Double Snare can and will destroy Jinzo.