If you choose to pay the blitz cost rather than the mana cost, you're still casting the spell. It goes on the stack and can be responded to and countered. You can cast a creature spell for its blitz cost only if you could cast that creature spell. Most of the time, this means during your main phase when the stack is empty.

If you pay the blitz cost to cast a creature spell, that permanent will be sacrificed only if it's still on the battlefield when that triggered ability resolves. If it dies or goes to another zone before then, it will stay where it is.

If the copied creature has {X} in its mana cost, X is 0.

If another creature becomes a copy of, or enters the battlefield as a copy of, the token, that creature will copy the creature card the token is copying. However, it won't have either haste or "When this creature dies, draw a card," and you won't sacrifice the new copy at the beginning of the next end step.

The token copies exactly what was printed on the original creature and nothing else (unless it's copying a creature that's a token or that's copying something else; see below). It doesn't copy whether the creature is tapped or untapped, whether it has any counters on it or Auras and/or Equipment attached to it, or any non-copy effects that changed its power, toughness, types, color, and so on. Most notably, if the target creature isn't normally a creature, the copy won't be a creature.

Any enters-the-battlefield abilities of the copied creature 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 creature card will also work.

The triggered ability that lets its controller draw a card triggers when it dies for any reason, not just when you sacrifice it during the end step.

If a copied creature is a token that isn't a copy of something else, the copy copies the original characteristics of that token as stated by the effect that created it.

If a creature enters the battlefield as a copy of or becomes a copy of a creature whose blitz cost was paid, the copy won't have haste, won't be sacrificed, and its controller won't draw a card when it dies.

If a copied creature is copying something else, the token you create will use the copiable values of the target creature. In most cases, it will just be a copy of whatever that creature is copying.

If Jaxis, the Troublemaker's ability creates multiple tokens due to a replacement effect (such as the one Doubling Season creates), you'll sacrifice each of them at the beginning of the next end step.

You don't have to attack with the creature with blitz unless another ability says you do.