Yes, you can.

No, it can't attack. A new attack declaration can't be made during an attack. In this case, you use this card to attack and use its [When Digivolving] [When Attacking] effect to play a Digimon. This card's [Your Turn] effect can be activated before the counter timing, but because you can't declare another attack during an attack, you won't be able to attack using this effect, even if you activate it.

No, it can't be played. "With the same names" also refers to a card with even just 1 of the same name as any of your Digimon. This effect can't play cards with the same name as [Sistermon Ciel].