I have a question about how MC plays out.

If I use a figure with MC that has 3 lightning bolts (targets) for the attack, & he hits all 3 opposing figures' defenses, then do I get to make an action with all 3 Mind Controlled targets on that action?
If so do I also take 3 clicks of damage if those figures are all 100 points or more in value?

Any help appreciated.

Yes.

Actually, you take into account the combined point values of all hit targets.
Say you successfully Mind Control one 100 points characters and two 75 points characters: you'd take 2 damage (100+75+75=250).

Also remember that at the start all 3 are considered friendly. After a target has been given an action it because unfriendly.