It does not, unless it has an effect that states otherwise.
Not manually, no. A monster that has declared an attack that turn, may not switch into defence mode. But it can be switched by the effect of other cards, including their own, in the case of Goblin Attack Force.
No, a 'Flip Summon' is a manual change from face-down defence to face-up attack position in one of your main phases. If the monster is flipped from an attack, or by an effect, then this is a Flip, but not a Flip Summon. Therefore regular Flip Effect monsters like Night Assailant will trigger from being attacked, but monsters that require Flip Summoning like Guardian Sphinx will not.
A monster in face-down Attack position is unable to declare attacks. It can be flipped or Flip Summoned, both actions will switch it into face-up Attack position. It can also have its battle position change by the controlling player, switching it from face-down Attack position to face-down Defence position.
In general, a restriction on changing a monster's battle position only applies to manual position changes, by the player. So If you took control of a monster with Creature Swap, you cannot manually change the battle position that turn. However that does not apply to other effects, they can be used to change the battle position. So Book of Moon would put it into face-down defence position as normal.
No, a monster cannot manually change battle position on the turn it was special summoned, though it can be changed by an effect.
No, it shouldn't, unless it says something along the lines of: "if this card is in face up attack position; ...<add effect here.>" In most cases, it doesn't change, though. If it is a flip effect, it means that the monster must be flip summoned to make the effect work. In other words, play the card in face down defense position, then flip it over to face up attack position on your next turn. Card flip effects are activated if the card is attacked while in face down position.
they entered the war
Yes. The 'cannot change battle position' limitation is only for manual changes such as flip summons or putting a monster into attack mode. The monster's position can still freely be changed by effects.
Yes, if you control a monster in defense mode and it is changed to attack mode during the Battle Phase by a card effect, it can attack. The "Zero Gravity" Trap card is an example of a card that can switch your monsters' battle position during the Battle Phase. But if the monster already attacked that turn, was switched to defense mode, then changed to attack mode again by an effect, it cannot attack again on that same turn.
Phillip hugged the monster happily.
The monster is flipped into face-up defense position and any battle damage that occurs is calculated. Afterwards the monster that was attacked remains on the field and is not sent to the Graveyard.Examples of monsters that cannot be destroyed in battle are Spirit Reaper and Marshmallon.If a monster attacks with an effect that enables it to deal damage equal to the difference in its ATK and the defending monster's DEF (like Twin-Sword Marauder or a monster equipped with Big Bang Shot), the damage is calculated but the monster is still not destroyed in battle.
Lord Voldemort placed on a curse on the position after he failed to get it.