New player here and apologize if this has already been asked/answered but, does his reaction fire if he is not participating in a conflict or even if he's bowed out? And to confirm, each reaction on a card can only fire once a round, unless otherwise stated?

All triggered abilities, on any card type, can be used:
- While bowed
- Once per round
- Can be used from home (ie. not participating in a conflict), unless the ability states otherwise (Lion's Pride Brawler must be attacking, Akodo Toturi must be participating)

From the Rules Reference

Bow, Bowed
* A card ability on a bowed card is active and can still engage with the game state. However, if a bowed card must bow as part of its cost to trigger an ability, it cannot bow again until it is readied, so the ability could not be triggered.

Action, Action Ability
* Unless otherwise noted by the ability, each action ability may be initiated only once each round.