questions about the damage increase when hitting enemies at the end of their attack animation

hey i am new to dark souls and today i noticed something. the item description of the spear says that you do increased damage if you time your attack at the end of the enemy swing. i tried this and i have some questions about this.

1. if you succeed with this, is there an audio cue? i think i noticed this.

2. i think i once heard the sound cue when i got hit by an enemy. so does this work on enemies too and will the sound cue then play aswell?

3. does this only work if you hit an enemy at the END of his swing, or does it also work if you hit him mid swing or while he does a flurry of swings?

4. does this only work with spears, or with every weapon?

5. how much dies the damage increase if you do this? does the damage increse depend on the weapon you are using?

thx! :)