'Casting a creature spell' means to pay the mana cost and put the creature spell on the stack. If this is allowed to resolve, then the creature enters the Battlefield.
An Ooze token is a creature that can be created. The token card is the representation of that creature.
No, unless they have haste.
A giant deck is a deck consisting of the creature type giant.
Whenever a creature with lifelink deals damage, (combat or otherwise) to a creature or player, you gain that much life.
If creature has Reach, it can block flying creatures without having to have flying itself.
Single cards that represent a creature (token) there are currently 199 that I am aware of.
No. You cannot kill the creature that is sacrificed in reponse to it being sacrificed as it is already gone.
If a creature has Intimidate, when it attacks, it can only be blocked by creatures that share a colour with it, or artifact creatures.
Creatures with Flying may block creatures that don't. Note that in Magic, creatures do not 'attack directly' as such, they are declared as attackers, and then creatures may be declared to block them. The creature with Flying in this case, can block creatures with, and without Flying.
The Coldsnap land 'Dark Depths' produces a Marit Lage token.
A creature with shroud cannot be targeted by instants, sorceries, or any other spells or abilities that target. However instants such as Evacuation will affect the creature because the spell does not target.
Hostility has a replacement effect for when your 'spell' deals damage to the opponent. Creatures are indeed summoned by casting a 'Creature Spell' but when this resolves, it is simply now just a 'creature'. Any damage they deal, effect or battle, is not 'spell' damage. I don't know if there are any situations where a Creature Spell can deal damage while it remains a spell. Damage dealt when creature spells are cycled, etc, are damage from an ability, not from a spell.