Question about deep wound

Lets say I'm using an axe and use eviscerate, doing 24 damage and lowering my foe's health by 20% for 17 seconds. Lets say 20% of his health of 50. Does that mean I do a total of 74 damage to him? After 17 seconds,would he get 50 health back?

yes, and yes. or if the condition is removed he gets that life back. also your numbers are a little low im sure you do like 70ish with evicerate and 80-100 with the deepwound.

What is your enemy is already low on health (lets say 50%) and you inflict deep wound on him? Would he still take extra damage from deep wound?

Lowering your target's *max* health by 20%. So yes, it does decrease the same amount, no matter how wounded he/she is.