Yes, as long as it's your own turn. If you want to activate them in the opponent's turn, you need to have Set them on the field during your own.
Since DD Sprite can only be summoned during your own turn, its trigger will activate in the opponent's Standby Phase.
As a trap card, you cannot activate it on the turn you Set it. However you can activate it in any turn after that, including your own, if you wish.
No. It is an Ignition Effect, meaning you may only activate Snipe Hunter's effect during your turn.
It is an Ignition Effect, so can only be activated in your turns.
'Activate' has two meanings when referring to continuous cards. To 'activate' the card is to flip it face-up from being set. To 'activate the effect' is to have a continuous card already face-up, and use a reusable effect on it. (a recent ruling allows you to 'activate the effect' once on the same chain link as 'activating the card', but that's not relevant here). For Hysteric Party, the cost of discarding one card is the cost you pay to activate the card, ie, to flip Hysteric Party face-up. Once you have done this, you cannot discard another card to summon Harpies again, it is not a reusable 'activate the effect' card, like Royal Oppression.
You can only activate a Quickplay Spell card from your hand in your own turn. If you want to activate it in the opponent's turn, you must Set it during your own turn.
Yes, as long as it's your own turn. If you want to activate them in the opponent's turn, you need to have Set them on the field during your own.
Since DD Sprite can only be summoned during your own turn, its trigger will activate in the opponent's Standby Phase.
Yes, it is a Continuous Trap card with a Quick Effect. You can activate the card in any phase of the opponent's turn, and you can activate the effect of the card in any phase of the opponent's turn also.
As a trap card, you cannot activate it on the turn you Set it. However you can activate it in any turn after that, including your own, if you wish.
No. It is an Ignition Effect, meaning you may only activate Snipe Hunter's effect during your turn.
No, Quickplay Spell Cards must be Set on the field on a previous turn, if you wish to activate them during the opponent's turn.
No you cannot. Even if you set cards on your oppoent's turn, the rule for Traps is that they can only be activated during the turn after they are set. Once your turn rolls around you activate your new set card.
This was only possible during the Puffle Party 2012 yet. Although you might get to turn into a puffle next party.
Double Summon's effect is only active during the turn in which you activate it.
Stardust Phantom's first effect is a Trigger, and will activate whenever the condition is met. That means it can activate in your turn or your opponent's turn.Stardust Phantom's second effect is an Ignition Effect and can only be activated in your own turns. The protective effect it applies to a Synchro Monster will work like a continuous effect, it can be protected once per turn in either player's turn.