Q1: Can I use this card's Your Turn effect to digivolve a Digimon other than the played Digimon?
Yes, you can.
Willis BT17-088 U [Start of Your Main Phase] [On Play] 1 of your green Digimon gets +2000 DP until the end of your opponent's turn. [Your Turn] When one of your Digimon with [Terriermon] or [Lopmon] in its name is played, by suspending this Tamer, 1 of your such Digimon may digivolve into a Digimon card in the hand with the digivolution cost reduced by 2. --- [Security] Play this card without paying the cost.
Willis BT17-088 U [Start of Your Main Phase] [On Play] 1 of your green Digimon gets +2000 DP until the end of your opponent's turn. [Your Turn] When one of your Digimon with [Terriermon] or [Lopmon] in its name is played, by suspending this Tamer, 1 of your such Digimon may digivolve into a Digimon card in the hand with the digivolution cost reduced by 2. --- [Security] Play this card without paying the cost.
Willis BT17-088 U [On Play] [Start of Your Main Phase] 1 of your green Digimon gets +2000 DP until the end of your opponent's turn. [Your Turn] When one of your Digimon with [Terriermon] or [Lopmon] in its name is played, by suspending this Tamer, 1 of your Digimon with [Terriermon] or [Lopmon] in its name may digivolve into a Digimon card in the hand with the digivolution cost reduced by 2. --- [Security] Play this card without paying the cost.
ウォレス BT17-088 U 【自分のメインフェイズ開始時】【登場時】相手のターン終了まで、緑の自分のデジモン1体をDP+2000。 【自分のターン】名称に「テリアモン」/「ロップモン」を含む自分のデジモンが登場したとき、このテイマーをレストさせることで、名称に「テリアモン」/「ロップモン」を含む自分のデジモン1体を手札のデジモンカードに支払う進化コスト-2で進化できる。 --- 【セキュリティ】このカードをコストを支払わずに登場させる。