

Q1: Can I use this card's Main effect to return Digimon cards from my opponent's trash to the bottom of the deck until the total of their levels is 8 or less?
No, you can't. A "by doing X" condition can't be met if only some of the required actions are performed. In the case of this card's Main effect, you must return Digimon cards to the bottom of the deck until the total value is the specified level.
Q2: If I use this card's Main effect to return a level 3 and a level 6 Digimon card from my opponent's trash to the bottom of the deck, what level of Digimon cards can I play from my trash?
You can play level 3 and level 6 Digimon cards. 1 of each card with the same level as the returned cards can be played.
Q3: If I use this card's Main effect to return 3 level 3 Digimon cards from my opponent's trash to the bottom of the deck, can I play 3 level 3 Digimon cards from my trash?
Yes, you can. 1 of each card with the same level as the returned cards can be played.
Apparition Legion BT20-098 U LIBERATOR [Main] By returning 9 levels' total worth of Digimon cards from your opponent's trash to the bottom of the deck, you may play 1 [Ghost] trait Digimon card of each returned card's level from your trash without paying the costs. Then, the Digimon this effect played gain <Rush> and <Blocker> until the end of your opponent's turn. --- [Security] You may play 1 level 5 or lower Digimon card with the [Ghost] trait from your trash without paying the cost.
Apparition Legion BT20-098 U LIBERATOR [Main] By returning up to 9 levels' total worth of Digimon cards from your opponent's trash to the bottom of the deck, you may play 1 [Ghost] trait Digimon card of each returned card's level from your trash without paying the costs. Then, the Digimon this effect played gain <Rush> and <Blocker> until the end of your opponent's turn. --- [Security] You may play 1 level 5 or lower Digimon card with the [Ghost] trait from your trash without paying the cost.
Apparition Legion BT20-098 U LIBERATOR [Main] By returning 9 levels' total worth of Digimon cards from your opponent's trash to the bottom of the deck, you may play 1 [Ghost] trait Digimon card of each returned card's level from your trash without paying the costs. Then, the Digimon this effect played gain <Rush> and <Blocker> until the end of your opponent's turn. --- [Security] You may play 1 level 5 or lower Digimon card with the [Ghost] trait from your trash without paying the cost.
アパリションレギオン BT20-098 U リベレイター 【メイン】相手のトラッシュから、デジモンカードをLv.合計9になるようにデッキの下に戻すことで、自分のトラッシュから、特徴に「ゴースト型」を持ち、戻したカードと同じLv.のデジモンカード1枚ずつをコストを支払わずに登場できる。その後、この効果で登場したデジモンは相手のターン終了まで、≪速攻≫と≪ブロッカー≫を得る。 --- 【セキュリティ】自分のトラッシュから、特徴に「ゴースト型」を持つLv.5以下のデジモンカード1枚をコストを支払わずに登場できる。