The first one that resolves will negate the effect of the other one when it resolves to the field. The other one will be face-up on the field doing nothing until the first one leaves the field.
Yes, the effect only works after the effect resolves, so you can activate it in a chain to "Royal Decree". Cards like "Dust Tornado" can even destroy "Royal Decree" as it is chained to "Royal Decree"'s activation. When the chain resolves, "Dust Tornado" will destroy "Royal Decree" and "Royal Decree"'s effect will disappear since it is no longer on the field.
Yes, as long as the spell card is a Quickplay Spell, and the trap card is not a Counter Trap. So you cannot chain Monster Reborn to any trap. Nor can you chain Book of Moon to a Counter Trap, for example.
As an Optional Trigger, the destruction must be the last thing to happen. If it is destroyed, but something else 'happens' (a summon, a resolution, etc) before it gets chance to activate, then it has 'missed the timing' and is not allowed to activate at all.
1. Activate "Acid Rain"2. Activate "Call of the Haunted" targeting "Labyrinth Tank"3. Chain "Mispolymerization"4. Activate "Stop Defense" targeting "Electromagnetic Bagworm"5. Activate "Scroll of Bewitchment" targeting "Electromagnetic Bagworm" andchoosing DARK6. Activate "Overload Fusion" targeting "Labyrinth Tank"7. Attack "Electromagnetic Bagworm" with "Luminous Soldier"8. Attack with "Labyrinth Tank" Answer from Yu-Gi-Oh! World Championship 2007 Puzzle Guide
If royal decree is not in the chain, yes. However, if your opponent activates, for example, mirror force, then you chain trap jammer, then they use a trap jammer, you would not be able to activate royal decree because it's got a spell speed of 2. Only counter traps have a spell speed of 3 and to counter a card, you need to play a card that is the same or a higher spell speed. So in the example, mirror force would not be negated because their jammer would negate yours.
Because you tribute it as a cost, it's not possible to activate it more than once in the same chain.
That would not be legal. Starlight Road has to chain directly to the card it will be countering. That means if you activate a destruction effect and the opponent chains their Starlight Road, you can't use yours.
As a Spell Speed 2 card, you cannot chain Royal Decree to a Counter Trap. However if Royal Decree is already active, any Counter Traps that try to resolve, will be negated.
Yes, you can chain to a card(s) that activate during the Standby Phase.
Once a monster is successfully summoned, the chain afterwards is the summon response chain. Cards like Bottomless Trap Hole are valid at any link in this chain, and multiple response cards can be used against the same summon. So after a successful summon, Player A passes priority to his opponent, either by activation an Ignition Effect, Trigger, or Spell Speed 2 card, or by passing it manually. Whatever he does, Player B can activate a Bottomless Trap Hole, either adding it as chain link 2 or starting a chain. Player A could activate something like Royal Decree, which will resolve first and negate the Bottomless Trap Hole. So before anything resolves, Player B could add a second BTH to the chain. This second BTH will resolve first, destroying and removing the monster from play. Royal Decree will resolve and become active next. The first BTH won't do anything now, it will get negated, and even if it didn't, there's nothing for it to affect. Note though that if Player A had used a Counter Trap against the BTH, then a second cannot be used, as a Spell Speed 2 card can't be chained to Spell Speed 3.
The turn player has Priority, so can activate Chaos Sorcerer's effect as chain link 1. Fiendish Chain can be chained to this. Fiendish Chain will resolve first, so Chaos Sorcerer's effect will be negated when it tries to resolve.
It can't negate continuous 'effects' because it has to chain to activations. Continuous effects do not activate. It can chain to and negate the activation of a continuous spell or trap. If the continuous spell or trap has its activation negated, then the card is destroyed and goes to the graveyard.