same theory as kicker
you don't get to pay it unless you played it from hand
This isn't correct.
A) You can pay the kicker cost any time you play a spell with kicker. That means playing a [card]Dismantling Blow[/card] from your graveyard while under the influence of [card]Yawgmoths Will[/card] or playing a [card]Jilt[/card] off an [card]Isochron Scepter[/card] both give you the opportunity to pay the kicker cost.
B) In reference to the Etched Oracle, again, where you played it from doesn't matter. You could play this from your graveyard and it would still get the counters for the right types of mana. If, however, it leaves play and then returns to play, it will not get any counters because no mana would have been paid for it at that time.
Playing a card is not the same as putting a card into play.
Putting a spell on the stack is not necessarily the same as playing a spell.