The yellow lantern is continual so if a fig picks it up the effect is still in place.

If a multi base fig picks it up where is the 4 square range measured from? For a double base fig would it be from both squares it occupies?

Thats a good question. Where is Questions when you need him? I'm sure he or an Orange will comment on this soon.

Pick a square then count from there.

Thank you

Does the controller of the figure holding the object make that decision or is it the active player or the owner of the object?

Does that decision last until that figure drops the object or until end of turn?

I'd rule that it is the controller of whomever is holding the object that gets to decide.

As far as when it ends, that's a toughie... there really is absolutely no precdent for something like this that I can think of. I'd probably let them decide on an action by action basis (like wild cards or canceling powers), but there is no evidence at all to support that ruling... it is just what I'd do if asked at one of my events.