>1. Would the workers have killed the new queen after I finally release her from the cage, or would they let the queens fight it out?
They would let the queens fight it out. If they don't then the workers will decide. Laying queens sometimes won't. The younger they are the more likely they will fight. Virgins are out for blood. Laying queens are busy laying eggs.
>2. The attendeds were dead in the cage, would the workers have killed them through the screen?
Yes.
>3. I understand how a new queen will kill other queen cells.. but what happens when 2 queens meet in a hive. Do they fight and try and sting each other?
Two virgins? Yes. Two young laying queens? Maybe. Two old laying queens. Seldom.
> Chances of losing them both?
Low, but possible.
> Will the workers get involved?
Only if the queens aren't willing to fight.
I've watched it in an observation hive. You should try it. It did take them hours and hours to find each other and many false starts to the fight followed by hours of wandering around and then another tussle.
Here's Huber's account:
"While the combat lasts, the bees move with great rapidity; they fly on all sides; and, gliding between the combs, conceal their motions from the observer. For my part, though using the most favourable hives, I have never seen a combat between the queens and workers, but I have very often beheld one between the queens themselves."
"They immediately began fighting, but came to disengage themselves from each other. However they fought several times during the night without anything decisive. Next day, the thirteenth, we witnessed the death of one, which fell by the wounds of her enemy. This duel was quite similar to what is said of the combats of queens."
"they will pursue each other, and fight until the throne remain with her that is victorious. Far from opposing such duels, the other bees rather seem to excite the combatants."
--New Observations on the Natural History Of Bees by François Huber
http://www.bushfarms.com/huber.htm