How does the "target opponent moves to a different position" effect work? Does it oblige him/her to change from a row to another or left-right will do the trick? Can he switch possition with another character? Do you choose where he moves the character? Can he move from an area to another?

And what about Lockjaw?

Activate ---> Exchange the position of Lockjaw and a Fantastic Four character you control if they are both in the same area.

If you attack a FF character and activate him you attack lockjaw instead?

The opponent must choose a new, empty place for the character to go
Either/both of those are fine.
No.
No.
Not unless the card doing the moving specifies so.
No - the character you are attacking remains a defender, but moves to lockjaw's position.

Thanks, you helped a lot. :D