Worldwaker Helm's first ability applies to all kinds of artifact tokens that its controller creates, not just Map tokens.

If the copied token has in its mana cost, X is 0. (Most tokens don't have a mana cost unless they're copying something else.)

The additional Map token won't have any abilities the other tokens were created with. Anything else specified in the effect creating the token (such as tapped or "Exile that token at end of combat") applies to both the original tokens and the Map.

You don't need to control the spell or ability that creates the tokens, but you do have to be the one creating the tokens for Worldwaker Helm's first ability to apply.

If the copied token is copying something else, then the new token enters the battlefield as whatever that token copied.

Any enters-the-battlefield abilities of the copied token will trigger when the token enters the battlefield. Any "as [this permanent] enters the battlefield" or "[this permanent] enters the battlefield with" abilities of the copied token will also work.

The new token created by Worldwaker Helm's last ability copies the original characteristics of the target token as stated by the effect that created the target token and nothing else (unless that token is copying something else; see below). It doesn't copy whether the target token is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.