Your first question is answered by the compendium:
Q. What happens if a Pokemon with Rescue Energy attached is Knocked Out by an attack that normally sends cards to the Lost Zone?
A. The order of resolution for the effects can be decided by the owner of the Pokemon with Rescue Energy attached to it. So the Pokemon can either go to the Lost Zone and stay there, or use Rescue Energy to return the Pokemon to your hand. Any other cards such as Energy, Tools, etc. would still go to the Lost Zone if the attack specifies. (HS:Triumphant FAQ; Nov 4, 2010 PUI Rules Team)
So it is up to the owner of the pokemon that the rescue energy is attached to.
As for your second question, powers that do not state that they can only be used once per turn/game, such as http://pokebeach.com/scans/secret-wonders/7-gardevoir.jpg , can be used once by each of the pokemon with that power. So your answer is yes.
