If they sacrifice 100 goblins I take 100 damage despite the dissipation field? The damage is applied all at once and not as separate 1 damage triggers?
It doesn't really matter how they do. They can sacrifice all of their creatures at once, or they can let the activation resolve, then respond to the Field's trigger by sacrificing another creature before the Bombardment is returned to their hand.
No it does not. "It" is the creature that was returned by the Lunge, which was the Vessel, not any tokens created by the creature entering. The Archfiend has a triggered ability that triggers if it enters the battlefield from the graveyard, not a replacement effect. Likewise, with the Call, the Vessel would get the counters and not the token created by its enter the battlefield trigger.
Repeated Reverberation does nothing until it resolves, and it does not target anything. It has to resolve before it will make two copies of the next spell. So the first one is wrong, because the Reverberation must resolve before you cast the Reversal to get copies of the Reversal (and that means you won't be able to target the Reverberation with the Reversal since it's no longer on the stack by the time you want to cast the Reversal).
In your second example, you can cast the Reverberation, then respond with the Reversal on the Reverberation, but then you lose your Reversal (and the Reverberation is back in your hand), which doesn't seem to do much.
Since the Thrull has a black mana symbol and a white mana symbol in its mana cost (and nothing else is affecting its color), it is both a white and black spell. It would trigger Demon's Horn and Angel's Feather when it's cast.
Lurrus cares about the converted mana cost of the spell on the stack, not the card in your graveyard. If you have a Stonecoil Serpent in your graveyard and you want to cast it via Lurrus' ability, the largest value you can choose for X is 2. If you pick 3 or more, then the converted mana cost of the spell on the stack is 3 or more, and not castable via Lurrus' ability.
The Owl contribute 4 to devotion to white, 4 to devotion to blue, and 4 to devotion to blue and white, all at the same time. You don't just pick one color or the other, it contributes to all of them at the same time. In this case, your devotion to blue is 5, and your devotion to white is 5, so both Heliod and Thassa will be creatures.
All is Dust doesn't target anything (you can tell because it doesn't use the word 'target' and is not an aura on the stack). But as for your question, they won't be sacrificed. A card with devoid is colorless, and All is Dust will only make players sacrifice colored permanents. Since the creature with devoid is colorless, it won't be sacrificed.
Life and Limb doesn't have to. Because of this rule, it only applies to permanents of that type on the battlefield:
109.2. If a spell or ability uses a description of an object that includes a card type or subtype, but doesn’t include the word “card,” “spell,” “source,” or “scheme,” it means a permanent of that card type or subtype on the battlefield.
Life and Limb just says "All Forests and all Saprolings", so it only affects Forests and Saprolings on the battlefield, not Forest cards or Saproling cards in other zones like the library.
When the storm trigger resolves, you put all of the storm copies on the stack. Each copy will trigger the Leyline (because each copy is its own spell), but those triggers can't go on the stack until after you're done resolving the storm trigger. So all 19 of the storm copies will go on the stack, then all 19 of the Leyline triggers will go on the stack, and the 19 Leyline triggers will resolve first, before any of the storm copies resolve.
With trample, you don't take effects that would increase or decrease the damage into account when determining if it has lethal damage assigned to it. That means that you don't get to take Torbran's effect into account when you're assigning damage. A 4/4 with trample that's blocked by a 1/1 would have to assign 1 damage to the 1/1 and can assign the remaining 3 damage to the defending player - then when we would deal the damage, the damage that would be dealt to the 1/1 is increased by 2 to 3 damage, and the damage that would be dealt to the opponent is increased by 2, and they take 5 damage.
It doesn't really matter how they do. They can sacrifice all of their creatures at once, or they can let the activation resolve, then respond to the Field's trigger by sacrificing another creature before the Bombardment is returned to their hand.
In your second example, you can cast the Reverberation, then respond with the Reversal on the Reverberation, but then you lose your Reversal (and the Reverberation is back in your hand), which doesn't seem to do much.
2. No. Loss of life is not damage. Losing a life to activate a fetchland's ability doesn't make you a legal target for the Drop.
If Sarkhan isn't on top, then it's not a planeswalker and won't be affected by the +1 ability on future turns.
Life and Limb just says "All Forests and all Saprolings", so it only affects Forests and Saprolings on the battlefield, not Forest cards or Saproling cards in other zones like the library.