To get cards:
Play alot. Level alot. Play offline (story & free battle) AND online alot. Or just be lucky.
As for full heal creatures, the only one I ever used was a Dubchic. 'Cept for the Dubchich (the ultimate mode version), that's the only full heal enemy card I know.
To have a card return to your hand, you can use Escape. Instead of being destroyed, the card returns to your hand. Can only be used in Defense phase.
Another card you can use is called Card Return. It returns your recent discarded and destroyed cards to your hand. Can only be used during Set phase.
And its called the discard pile not the graveyard
--d-_-b