QWhile my center holomem is a red 2nd holomem, and my collab holomem is hBP01-050[Kazama Iroha], my opponent used Arts on my hBP01-050[Kazama Iroha].
In this case, can I use hSD13-001[Elizabeth Rose Bloodflame]'s Oshi skill "Harbinger of Order" and choose my red 2nd holomem in the center position to take that damage instead?

AYes, you can.

QCan hBP01-050〈Kazama Iroha〉's Arts 'Bringing You Energy at Full Power!' be used even if the cheer deck is empty?

AYes, it can be used.

QWhen using hBP01-050〈Kazama Iroha〉's Arts 'Bringing You Energy at Full Power!' cheer sending ability, can you choose holomem to send cheers after checking cheer colors?

AYes, it is possible.
Turn the top card of the cheer deck face-up, then choose the holomem to send the cheer to.

QCan you use hBP01-009〈Amane Kanata〉's 'KonKanata~' while opponent's hBP01-050〈Kazama Iroha〉's gift 'Bodyguard' is active?

AYou can declare the use of Arts, but since you cannot properly choose the target, it will not be considered that Arts are used, and no damage can be dealt.

[Updated 2025/03/11] Even if hBP01-009 has hBP01-114 equipped, the ability 'When the holomem this tool is attached to uses Arts' does not activate.