If this card's [On Play] [When Digivolving] effect is used to treat [Marcus Damon] as a Digimon, can I use the part of the effect after "then" to attack using that [Marcus Damon]?

If this card's [On Play] [When Digivolving] effect is used to treat [Marcus Damon] as a Digimon, can I choose to not attack using the part of the effect after "then"?

Does this card's [All Turns] effect also trigger when a [Marcus Damon] treated as a Digimon is deleted?