For Chiv/Karma Scaling it works like this.
The base effect from Chiv skill * .5 to 1.5 depending on Karma.
So if 10 Chiv Heals you for 10 HP at 0 Karma, @Max positive Karma it should heal you for 15, and Max Negative Karma would heal you for 5.
If 100 Chivalry healed you for 30 @ 0 Karma, then it would be 45 @ max positive karma and 15 @Max negative
Serpent Arrow was unchanged. (In code serpent arrow seems capable of inflicting lethal poison with HIGH dex, archery and poisoning).
The Poison Resistance effect, acts as a passive chance to self cure poison. This does not prevent the character from being re-poisoned. The chance to cure is re-rolled on each poison tick. Since these ticks usually occur between 2-5 seconds, and the first tick takes place around 3 seconds.
This means that even if the resistance kicks in on the first tick the target is guaranteed to remain poisoned for at least 3 seconds unless they cure the poison by their own initiative.