some doubts about the effects

Hi, I have some doubts about the effects:

I wish I could handle the "instant" effects I just can't handle how many health points to remove/add. There's a way?
I would like to be able to manage the lasting effects where the health points to be removed are managed. Poison and wither exist as effects but are not limited. the first does not activate with the undead and the second with the wither. Is there a way to decide who to exclude/add when giving this type of effect?
I know that the freezing effect exists but it is not activated. Is there any way or do we have to "stick"? 
Since I'm managing custom enchantments I would like to be able to customize the particles to use and remove the "vanilla" ones. The point is that I should activate a function but I wouldn't know how to manage it for the duration of multiple levels. Is there any way?

These questions are mainly made to add them in the enchantments which is why I put it as an enchantment tag