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.
No, unless they have haste.
The ability "Defender" is actually a disability, a creature with defender cannot attack. Creatures with Defender often have "Wall" as their type.
An Ooze token is a creature that can be created. The token card is the representation of that creature.
Vigilance just means the creature does not tap when it attacks. It can be tapped by other spell or abilities, or as the cost for an ability that requires tapping - and must of course be untapped for it to be able to even declare an attack.
A giant deck is a deck consisting of the creature type giant.
'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.
Whenever a creature with lifelink deals damage, (combat or otherwise) to a creature or player, you gain that much life.
Creatures are not brought into play tapped, but they have summoning sickness preventing them from tapping to attack or to tap to activate any abilities unless they have the keyword "haste".
Single cards that represent a creature (token) there are currently 199 that I am aware of.
If creature has Reach, it can block flying creatures without having to have flying itself.
No. You cannot kill the creature that is sacrificed in reponse to it being sacrificed as it is already gone.
An 'attack' is what you do during the combat phase, you declare attackers by tapping them (or just declaring, if the creature has Vigilance) and these are now 'attacking monsters'.Tapping to use activated effects, even damage dealing ones, are not attackers, and the damage is not 'combat damage'.