Couple spell questions

[Josemite]

1. Is there a way to trigger when a unit gains or loses a buff?
2. Is there a way to dynamically alter unit's inherent attributes, specifically their priority, range, and base attack speed?
3. Is there a way to trigger when a unit gets healed (not based on "finishes casting ability" etc)

I'm assuming that all this would be have to be done in JASS, which I'm still learning, so any help would be much appreciated

 

[Need_O2]

1- Yes if you are too pro
2- with a weird way (you add %1 speed bonus multiple times for example) wont work for range
3- Health of some unit becomes max health of that unit ?