Q1: I am in a situation where I have my Digimon with a minus DP. What happens if I use this card's Main effect to select that Digimon with a minus DP?
The number will be unaffected by DP minus. For example, if you choose a Digimon with an original DP of 5000 (current DP is 3000) that is DP-2000 due to the card's Main effect, that Digimon will no longer be DP minus and its DP will be 5000.
Red Card BT19-089 C While your opponent has a white Digimon or Tamer, you may ignore this card's color requirements. [Main] Until the end of your opponent's turn, 1 of your Digimon is unaffected by your opponent's Option cards and its DP can't be reduced. --- [Security] Add this card to the hand.
Red Card BT19-089 C While your opponent has a white Digimon or Tamer, you may ignore this card's color requirements. [Main] Until the end of your opponent's turn, 1 of your Digimon isn't affected by the effects of your opponent's Option cards and it can't have its DP reduced. --- [Security] Add this card to the hand.
レッドカード BT19-089 C 白の相手のデジモン/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】相手のターン終了まで、自分のデジモン1体は相手のオプションカードの効果を受けず、DPをマイナスされない。 --- 【セキュリティ】このカードを手札に加える。