Each token copies exactly what was printed on the original card and nothing else, except the characteristics it specifically modifies. It doesn't copy any information about the object the card was before it was put into your graveyard.

The tokens are Zombies instead of their other types (unlike Zombies created by an eternalize ability) and are black instead of their other colors. Their power and toughness are 4/4. These are copiable values of the tokens that other effects may copy.

Unlike the tokens created by an eternalize ability, the tokens have the mana cost and thus converted mana cost of the cards they're copying.

If a card copied by one of the tokens had any "when [this permanent] enters the battlefield" abilities, then the token also has those abilities and will trigger them when it's created. Similarly, any "as [this permanent] enters the battlefield" or "[this permanent] enters the battlefield with" abilities that the token has copied will also work.

There are many important moments in the story, but the most crucial—called "story spotlights"—are shown on cards. You can read more about these events in the official Magic fiction at http://www.mtgstory.com.