Questions about bleed damage formula

# Context
I felt like making an axe thrower. I saw that berserker ascendancy, instantly thought axes are fun, remembered trolls throwing axes in other games, my frenzy throw barb in another game, some flashbacks from Vikings... and i instantly thought i want to have that playstyle again.

...so i ended up with theorycrafting a ranged berserker that bleeds enemies as he moved on the map.

# Factors
Berserker
Iron Grip passive
Spectral Throw (because i can't find another skill that throws melee weapons)

# Questions:

1) From wiki : "Bleed deals physical damage over time. The amount is based on the base damage of the physical damage that caused it"

What is considered base damage?

2) Does projectile damage affect bleed damage?

3) Is there a general formula for bleed damage?

4) Does crit chance/dmg affect base dmg for bleed damage?

5) Does crit chance/dmg affect bleed damage itself?

Most of your answers can be found here I think:
https://pathofexile.gamepedia.com/Bleed

Spectral throw has the projectile tag, so will be affected by projectile damage, which will in turn affect the bleed calculation.

I've already read the wiki section for bleed, but some parts aren't clear.

After watching ZiggyD's video, https://www.youtube.com/watch?v=JqifwelsCQ4

I learned that crit CAN affect, in some manner, ailments (and bleed is an ailment) via "Perfect Agony" passive.

@Napalm your statement contradicts his video, in which he says projectile damage doesn't affect ailments damage.

..i have to learn how to properly do my own tests.

With this said, i made watched the video and wrote it down.
Hopefully others looking for similar info will be helped by it.

DISCLAIMER : his video is written for 3.0 patch..i hope 3.5 retains this info.

Ailments
(non-ele) : bleed, poison
(ele) : ignite, shock, chill, freeze

I. bleed, poison
- is not based on initial hit
- are a separate damage roll
- scaling initial hit DOES NOT scale DoT ailments
DOT = (convert_to_ailment_dmg)[(base_damage + added_damage) * skill_dmg_effectiveness ] * relevant_scaling_modifiers

II. Ele ailments = ignite, chill, freeze, shock
- these last 3 work with normal crit as well

# base_damage
- for bleed = flat phys dmg on weapon scaled by local modifiers (% incr phys dmg and adds x-y phys dmg on wep)
- spells = flat dmg written from skill gem

# added_damage = any other source of flat damage
for bleed, stuff like
- iron rings + x-y
- abyssus adds 40-60 phys dmg
- chance to bleed support
etc.

for ignite
- added flat dmg from Anger aura
- jewely added flat dmg
- added fire damage support
etc.

# skill_dmg_effectiveness
1)effectiveness of added damage
- written on skill gem (if not, effectiveness = 100%)
- generally aoe scales less
- single target scales more

2) deals % of base damage written on skill gem

# relevant_scaling_modifiers
bleed = 210% per second while moving, 70% / second while stationary WHICH DOESN'T STACK.... UNLESS you take Crimson Dance passive, which makes it flat 35% stackable 8 times (good for bosses)
ignite = 40% per second (4 sec)
poison = 20% per second (2 sec) -- stacks

regular critical strike multiplier does not apply to ailments UNLESS you take the "Perfect Agony" passive
new critical strike multiplier for ailments = "damage multiplier for ailments from critical strikes" (default 150%)

after that come in passives



How to increase ailment damage?
shock
vulnerability curse
flammability curse (for ignites)
lower their resistance
intimidate (10% from deceiver belt)
temporal chains (by duration)

Things NOT scaling ailment damage
- increased dmg with specific weapon type (e.g. % increased phys dmg with axes)
- "attack damage"
- melee, projectile, spell, area damage
- crit dmg multiplier (unless you have Perfect Agony)
- assassin's mark extra dmg multi (even with Perfect Agony)
- increased dmg on hit
- point blank, chin sol
- ele penetration (including inquisitor effect)
- ailments are NOT skill effects (so no incr. duration support gem or Potency of Will passive...unless you use Viper Strike / Puncture skills)

Mitigating bleed
- armor doesn't matter
- endurance charges matter

Ok, well Ziggy knows a lot more than me so I'd trust him.
If bleed only scales from flat plus damage and not any other initial hit scaling, (which does kinda make sense) it explains why I always struggled to get much effective bleed damage compared to hits.
You're correct that crit only affects bleed damage with Perfect Agony. Most people seem to believe this isn't worthwhile, I think I've only seen a few poison builds which consider it.
It seems that you're looking in the right places for info, I don't think that there's anything in 3.0 - 3.5 that would invalidate Ziggy's video, but can't be certain. For now I'll be quiet and hope someone that's more of an expert comes along! Good luck.

Edit: found Mathil did a video on a bleed build a couple of weeks ago: https://www.youtube.com/watch?v=fawotAG-vz0