Q1: If the 3 cards revealed for this card's Main effect don't include a card with the LIBERATOR trait, can I still play 1 card with the LIBERATOR trait and a play cost of 3 or less from my hand without paying the cost?
Yes, you can. You can activate the part of the effect after "then" regardless of whether or not you could add a card with the LIBERATOR trait to your hand.
Digimon Liberator P-151 P LIBERATOR While you have a Digimon or Tamer with the [LIBERATOR] trait, you may ignore this card's color requirements. [Main] Reveal the top 3 cards of your deck. Add 1 card with the [LIBERATOR] trait among them to the hand. Return the rest to the bottom of the deck. Then, you may play 1 card with the [LIBERATOR] trait and a play cost of 3 or less from your hand without paying the cost. --- [Security] Activate this card's [Main] effects.
Digimon Liberator P-151 P LIBERATOR While you have a Digimon or Tamer with the [LIBERATOR] trait, you may ignore this card's color requirements. [Main] Reveal the top 3 cards of your deck. Add 1 card with the [LIBERATOR] trait among them to your hand. Return the rest to the bottom of the deck in any order. Then, you may play 1 card with the [LIBERATOR] trait and a play cost of 3 or less from your hand without paying the cost. --- [Security] Activate this card's [Main] effect.
Digimon Liberator P-151 P LIBERATOR While you have a Digimon or Tamer with the [LIBERATOR] trait, you may ignore this card's color requirements. [Main] Reveal the top 3 cards of your deck. Add 1 card with the [LIBERATOR] trait among them to your hand. Return the rest to the bottom of the deck in any order. Then, you may play 1 card with the [LIBERATOR] trait and a play cost of 3 or less from your hand without paying the cost. ---
デジモンリベレイター P-151 P リベレイター 特徴に「リベレイター」を持つ自分のデジモン/テイマーがいる間、このカードは色条件を無視できる。 【メイン】自分のデッキの上から3枚オープンする。その中の特徴に「リベレイター」を持つカード1枚を手札に加える。残りはデッキの下に戻す。その後、自分の手札から、特徴に「リベレイター」を持つ登場コスト3以下のカード1枚をコストを支払わずに登場できる。