will massive damage move them 2 space ?
Only if it's against an enemy with 2+ hearts left.
for me it's really hard to bring paladin down when druid can get potion of him really easy (did we play it right? paladin can gain potion from other heroes success attack)
Yes, the hero player chooses which hero to give hearts or potions to, no matter which one rolled them. I hear that Ember Hounds in the Caverns of Roxor expansion can cause Choke though (Status effect : cannot use potions!).
how can resurrect charm work?
can I kill a hero who equip it first to prevent ressuection ?
Resurrection happens at the start of a round, so if you can kill the hero carrying it before that, then they can't use it!