Text (5th+errata): {3},{Tap}: Exile the top card of your library. Until the beginning of your next upkeep, you may play that card. [Oracle 2009/07/08]
You may play the card before the beginning of your next upkeep even if the Bottle leaves play. [D'Angelo 2008/07/01]
This is not considered to be drawing a card. [Aahz 1995/06/12]
The card is not part of your hand in any way. You cannot be forced to discard it due to a discard from hand effect. When you play it, it is played following rules as if it were being played from your hand (e.g. a sorcery is played as such and is not played as an instant). [Duelist Magazine #11, Page 56]
You cannot play a card from the Elkin Bottle onto an Ice Cauldron. [Duelist Magazine #11, Page 57] (See Ice Cauldron for more info)
Word of Command cannot be used to force a player to play a spell off the Bottle. [Aahz 1995/12/18]
You can get a creature card onto the Bottle when Enduring Renewal is in play. [D'Angelo 1995/12/04]
To "play a card" is to either announce a spell or to put a land into play using the main phase special action. [D'Angelo 1999/01/18]