QWhen your Life is 1 and your hBP01-013〈Amane Kanata〉 with hBP01-116〈Upao〉 attached is downed by opponent's Arts damage, can hBP01-116〈Upao〉's ability deal special damage to opponent holomem?

ANo, Damage is not dealt.
At HP 0, rule-based down resolution causes immediate loss without resolving hBP01-116 〈Upao）'s effect in standby.

QIf hBP01-013〈Amane Kanata〉's bloom effect 'Angel's Work' downs opponent's 1st holomem with buzz, does the extra 'If this holomem is downed, you get Life-2' reduce life?

ANo, it does not reduce.
The extra ability 'When this holomem is down, your life -2' is superseded by the ability 'your opponent's life does not reduce even if downed.', so the opponent's life does not decrease.