Attacks may be declared against players, or Planeswalkers. Attacks may not be declared against other creatures.
Some creatures or cards have "do x to deal x damage" (i.e. tap to deal one damage to target creature or player). This is different from attacking and you should not confuse the two.
In Magic: The Gathering, a land creature is a card that can be played as both a land and a creature. This means it can produce mana like a land and also attack or defend like a creature.
No, unless they have haste.
When a creature with trample attacks a creature with protection in Magic: The Gathering, the attacking creature can assign excess damage to the defending player or planeswalker, bypassing the protected creature.
No, a creature is not considered a spell in Magic: The Gathering.
No, a planeswalker is not considered a creature in Magic: The Gathering.
In Magic: The Gathering, when a creature is summoned or enters the battlefield, it cannot attack or use its abilities that require tapping until the player's next turn. This is called summoning sickness.
When you tap a target creature in Magic: The Gathering, it becomes exhausted and cannot attack or use its abilities until it untaps during the next untap step.
In Magic: The Gathering, excess damage dealt to a player is ignored, but excess damage dealt to a creature is removed at the end of the turn.
In Magic: The Gathering, the keyword "defender" means that a creature cannot attack, but it can block multiple attacking creatures at the same time.
No, in Magic: The Gathering, you can only block one creature with one creature.
In Magic: The Gathering, double attack triggers allow a creature to attack twice in the same turn. This ability is usually triggered by a specific card or effect, allowing the creature to attack once during the regular combat phase and then again during a second combat phase.
In Magic: The Gathering, the mechanic "sacrifice a creature to deal damage" typically involves a player sacrificing one of their creatures in order to deal damage to a target, such as a creature or player. This allows the player to use their creature as a resource to inflict damage on their opponent.