Ring Selection - At the beginning of your turn, you may choose a Ring, remove it from the Power Plant and place it on a friendly character's card. That character can use that Ring's effects as if it were a relic. When that character clears, return any Rings on its character card onto the Power Plant.

Drain a Ring's Power - Give a friendly character a free action and remove any one ring from the Power Plant. If you do, that character can either use Outwit or modify all of its combat values by +1, but only for this turn.
.....

say i have 3 characters on my team,

can all three drain a ring?

can one character drain 3 rings in one turn?

can i drain a ring, and use a ring in the same turn?

1. YEs as worded they can.
2. No only one free action per turn of the same free action.
3. Yes.