In Yugioh does a monster have to attack the newly Special Summoned monster during the Battle Phase if they already declared the attack?

Answer 1

Answer taken from the Official English Rulebook: After you've announced your attacking monster and the attack target monster during a Battle Step, the attack target might be removed from the field, or a new monster may be played onto the opponent's side of the field before the Damage Step, due to a card's effect. This causes a "Replay." When this occurs, you can choose to attack with the same monster again, or choose to attack with a different monster, or choose not to attack at all. Note that if you attack with a different monster, the first monster is still considered to have declared an attack, and it cannot attack again this turn.