Q1: Do I have to only choose cards from my hand or trash when I use this card's On Play When Digivolving effect to return 3 cards with the Three Musketeers trait to the top of the deck?
No, you can choose 3 cards with the Three Musketeers trait to return to the top of the deck from your hand, trash, or both. For example, you can choose 3 cards from your hand or choose a combination of 1 card from your hand and 2 cards from your trash.
Lv.4 Tankmon EX7-043 C Champion | Data | Cyborg [Digivolve] Lv.3 w/[Three Musketeers] in text: Cost 2 [On Play] [When Digivolving] By returning 3 cards with the [Three Musketeers] trait from your hand or trash to the top of the deck, <De-Digivolve 1> 1 of your opponent's Digimon. --- Inherited: <Reboot> (This Digimon also unsuspends in your opponent's unsuspend phase.)
Lv.4 Tankmon EX7-043 C Champion | Data | Cyborg [Digivolve] Lv.3 w/[Three Musketeers] in text: Cost 2 [On Play] [When Digivolving] By returning 3 cards with the [Three Musketeers] trait from your hand or trash to the top of the deck, <De-Digivolve 1> 1 of your opponent's Digimon. --- Inherited: <Reboot> (This Digimon also unsuspends in your opponent's unsuspend phase.)
Lv.4 Tankmon EX7-043 C Champion | Data | Cyborg [Digivolve] Lv.3 w/[Three Musketeers] in text: Cost 2 [On Play] [When Digivolving] By returning 3 cards with the [Three Musketeers] trait from your hand or trash to the top of the deck, <De-Digivolve 1> 1 of your opponent's Digimon. --- Inherited: <Reboot>.
Lv.4 タンクモン EX7-043 C 成熟期 | データ種 | サイボーグ型 「三銃士」の記述があるLv.3:コスト2 【登場時】【進化時】自分の手札/トラッシュから、特徴に「三銃士」を持つカード3枚をデッキの上に戻すことで、相手のデジモン1体を≪退化1≫。 --- Inherited: ≪再起動≫(このデジモンは相手のアクティブフェイズでもアクティブになる)