

Q1: Can I change the attack target of a Digimon that isn't affected by effects with an effect that "changes the attack target"?
Yes, you can.
Q2: A card stacked in a Digimon with this card in its digivolution cards is placed into its digivolution cards by an effect. At such times, if this card becomes that Digimon's top card, will this card's All Turns effect trigger?
Yes, it triggers.
Lv.5 Andromon BT26-054 U Ultimate | Vaccine | Cyborg/CS [On Play] [When Digivolving] You may play 1 [CS] trait Tamer card from your hand without paying the cost. This effect can't play cards with the same name as any of your Tamers. [All Turns] [Once Per Turn] When effects place [CS] trait Digimon cards in this Digimon's digivolution cards, this Digimon may digivolve into a [CS] trait Digimon card in the hand without paying the cost. --- [Opponent's Turn] [Once Per Turn] When one of your opponent's Digimon attacks, you may change the attack target to this Digimon.
Lv.5 Andromon BT26-054 U Ultimate | Vaccine | Cyborg/CS [Digivolve] Lv.4 w/[CS] trait: Cost 3 [On Play] [When Digivolving] You may play 1 [CS] trait Tamer card from your hand without paying the cost. This effect can't play cards with the same name as any of your Tamers. [All Turns] [Once Per Turn] When effects place [CS] trait Digimon cards in this Digimon's digivolution cards, this Digimon may digivolve into a [CS] trait Digimon card in the hand without paying the cost. --- [Opponent's Turn] [Once Per Turn] When one of your opponent's Digimon attacks, you may change the attack target to this Digimon.
Lv.5 Andromon BT26-054 U ultimate | Vaccine | Cyborg/CS [Digivolve] Lv.4 w/[CS] trait: Cost 3 [On Play] [When Digivolving] You may play 1 [CS] trait Tamer card from your hand without paying the cost. This effect can't play cards with the same name as any of your Tamers. [All Turns] [Once Per Turn] When effects place [CS] trait Digimon cards in this Digimon's digivolution cards, this Digimon may digivolve into a [CS] trait Digimon card in the hand without paying the cost. --- [Opponent's Turn] [Once Per Turn] When one of your opponent's Digimon attacks, you may change the attack target to this Digimon.
Lv.5 アンドロモン BT26-054 U 完全体 | ワクチン種 | サイボーグ型/CS 【登場時】【進化時】自分の手札から、特徴「CS」を持つテイマーカード1枚をコストを支払わず登場できる。この効果では、自分のテイマーと同じ名称のカードは登場できない。 【お互いのターン】[ターン1回]このデジモンの進化元に特徴「CS」を持つデジモンカードが効果で置かれたとき、このデジモンを手札の特徴「CS」を持つデジモンカードにコストを支払わず進化できる。 --- 【相手のターン】[ターン1回]相手のデジモンがアタックしたとき、アタックの対象をこのデジモンに変更できる。