Q1: This Digimon attacks my opponent, then my opponent blocks. Does this card's All Turns effect activate?
Yes, blocking causes the attack target to switch, so the effect activates.
Q2: Does this card's All Turns effect activate even when the attack whose target is switched was made by one of my other Digimon or an opponent's Digimon?
Yes, it activates.
Lv.6 WarGreymon BT12-070 SR Mega | Vaccine | Dragonkin Digivolve: 3 from Lv.5 w/[MetalGreymon] in name <Raid> (When this Digimon attacks, you may switch the target of attack to 1 of your opponent's unsuspended Digimon with the highest DP.)[When Digivolving] This Digimon gets +3000 DP and <Reboot> until the end of your opponent's turn.[All Turns] [Once Per Turn] If an attack target is switched, unsuspend this Digimon.
Lv.6 WarGreymon BT12-070 SR Mega | Vaccine | Dragonkin Digivolve: 3 from Lv.5 w/[MetalGreymon] in name <Raid> (When this Digimon attacks, you may switch the target of attack to 1 of your opponent's unsuspended Digimon with the highest DP.) [When Digivolving] Until the end of your opponent's turn, this Digimon gets +3000 DP and gains <Reboot>. [All Turns] [Once Per Turn] When an attack target is switched, unsuspend this Digimon.
Lv.6 WarGreymon BT12-070 SR Mega | Vaccine | Dragonkin [Digivolve] Lv.5 w/[MetalGreymon] in name: Cost 3 <Raid> [When Digivolving] Until the end of your opponent's turn, this Digimon gets +3000 DP and <Reboot>. [All Turns] [Once Per Turn] When an attack target is switched, unsuspend this Digimon.
Lv.6 ウォーグレイモン BT12-070 SR 究極体 | ワクチン種 | 竜人型 『名称に「メタルグレイモン」を含むLv.5』から3 ≪突進≫(このデジモンがアタックしたとき、アタックの対象を最もDPの高いアクティブ状態の相手のデジモン1体に変更できる) 【進化時】次の相手のターン終了まで、このデジモンをDP+3000し、≪再起動≫を得る。 【お互いのターン】[ターンに1回]アタックの対象が変更されたとき、このデジモンをアクティブにする。