Hello Deiwos,
According to this:
https://tos.neet.tv/skills/41101
Healing Factor has a cap of 27 seconds in pvp. I believe skill lvl 3 and ownards would be capped already (so higher skill lvls wouldnt provide more duration).
And according to this:
https://tos.neet.tv/skills/41103
Bloodletting lasts 15 + 2 * SkillLv seconds in pvp.
Beak Mask does not have any extra limitation for pvp. No reduced duration or anything. But it will only work for yourself while Bloodletting works for the whole party.
Not sure what you mean by that, Bloodletting does not have a “number of hits” limitation that it can protect you from (like Prophecy). It will protect against all lvl 2 or lower debuffs until the duration is over.
I believe the duration to be the same in PvP arena and GvG, with their reduced values.