2020-06-23 : Canopy Stalker's triggered ability counts itself, as well as any other creatures that die before the triggered ability resolves.

2020-06-23 : If each creature the defending player controls can't block for any reason (such as being tapped), then Canopy Stalker isn't blocked. If there's a cost associated with blocking Canopy Stalker, the defending player isn't forced to pay that cost, so it doesn't have to be blocked in that case either.

2020-06-23 : If your life total is brought to 0 or less at the same time that Canopy Stalker is dealt lethal damage, you lose the game before its last ability goes on the stack.

2020-06-23 : Only one creature is required to block Canopy Stalker. Other creatures may also block it, and are free to block other creatures or not block at all.

2020-06-23 : The defending player, not you, chooses which creature blocks Canopy Stalker.