Because all attackers are declared at the same time, the returned creature can't attack during the same combat it returns, even if it has haste.

If Drana attacks a planeswalker, that planeswalker's controller is the defending player.

The returned creature remains a Vampire in addition to its other types even after Drana leaves the battlefield.

The defending player chooses a card and you put it onto the battlefield all while Drana's ability is resolving. No player may take actions in between those events.