Is this an accurate description of how armor works across the Dark Souls series in PvE?

Introduction
I've seen a number of posts arguing back and forth about the effectiveness of armor across the Dark Souls series, but I've never found anything that spells out the actual math. Do the descriptions below accurately capture how armor works in the different games?
I'm looking to confirm (or correct) my understanding of the mechanics to help me evaluate different build options. For example, if I feel like I'm taking a lot of damage while wearing the Leather Set, knowing these calculations would help me figure out what kind of difference I might expect from using the Elite Knight Set instead.
Dark Souls 1
In DS1, armor is flat damage reduction. Suppose that a monster hits me with a Strike attack that deals 300 dmg. I'm an SL 4 Warrior wearing a full set of Elite Knight armor +10. That gives me Strike Def of 244, so I take 300  244 = 56 damage. Is that correct?
Dark Souls 2
In DS2, armor is still flat damage reduction, but the numbers are generally bigger. Suppose that a monster hits me with a Strike attack that deals 800 dmg. I'm an SL 12 Warrior wearing a full set of Elite Knight armor. That gives me Strike Def of 565, so I take 800  565 = 235 damage. Is that correct?
Dark Souls 3
In DS3, armor is a combination of flat damage reduction and % mitigation. Suppose that a monster hits me with a Strike attack that deals 300 dmg. I'm an SL 7 Warrior wearing a full set of Elite Knight armor. That gives me Strike Def of 87 and a Strike Mitigation % of 20.952, so I take (300  87) * (1  0.20952) = 168.37224 damage. Is that correct?
Other Questions
My understanding is that some attacks do mixed damage, such as a flaming sword doing showing and fire. How do those damage calculations work?

Dark Souls 1
The damage formula is available on http://darksouls.wikidot.com/damagecalculation . There is also a google sheet with the formulas builtin is available https://docs.google.com/spreadsheets/d/1tIgJNuYP__2GSz_R3XEw_KQkTSnmk84wnz7nu04G3w/edit?usp=sharing , and also https://docs.google.com/spreadsheets/d/1hn_XmEN6IUjBbtHYXiPz2BMotv8DUy6lHCgYsx7lXsA/edit#gid=0 with a 2d graph of damage vs attack.
This is for PvP, as it uses player defensive stats and player weapons, but the same principles will hold for PvE. I don't know if the full monster stats are available for exact calculations, but the general idea is there.
In general, defense is subtractive, with nonlinear slope; there are points where excessive defense/damage will do fixed damage and completely ignore any additional/reduced defense. As it is subtractive, it will do a better job of blocking multiple weak attacks than fewer heavy attacks.
Mixed Damage
Each damage type is calculated separately, against the full defense value for that type, and the result is added together. Because defense is subtractive, this typically means mixed damage types fare poorly, as it's effectively two separate (weaker) attacks. An exception would be if an enemy is specifically weak to a damage type; then the physical portion would still be reduced but the elemental aspect would do more damage.
Dark Souls 2
https://www.reddit.com/r/DarkSouls2/comments/q7xv9l/dark_souls_ii_damage_calculation_formula_final/ links to https://docs.google.com/document/d/1hfKeAv2M7LzQ0xnYFvD9sKGDd645Pjrm/edit . Dark souls 2 appears to not use a step function, and is just purely subtractive with a bunch of modifiers. Assuming this is accurate, weapon attacks can do 0 damage, unlike in 1.
For PvE, there's an additional multiplier (mentioned in the formula) for enemies that are weak/strong to a specific damage type. This information is available on https://www.reddit.com/r/DarkSouls2/comments/nml7t0/physical_resistance_of_every_enemy_in_the_game/ . To the best of my knowledge this is always just 100% for players.
Mixed damage
Mixed damage is completely changed, due to the change to elemental damage. Elemental damage resist is purely proportional, scaled against the target's defense. 900 defense in a stat is immunity; 0 defense in a stat is full damage. Each point of defense is another 0.1% reduction to that stat.
Because of this change, mixed weapons will do less physical damage (since that's still subtractive, and physical damage is always lower for mixed weapons), but the elemental damage will not be subtracted. It is only resisted by the proportional reduction.
Dark Souls 3
The formula is on http://darksouls3.wikidot.com/combatgamemechanics again; there is once again a step function with 5 breakpoints, and from a glance it appears to be identical to the dark souls 1 formula.
I honestly can't tell from reading the wiki if absorption exists for physical defenses, or if it's the same mechanic as dark souls 2.