With how many heroes there are on both sides and them not killable, I think you will see atleast one side have a hero in every battle. As for their special abilities, the only ones that really matter to gameplay that we know of is luke and the droids. You solve this by the quickest way to get technology is by stealing it with the droids. But if you can't use them there should be a rebel research center that takes longer. More realistic, the rebels researched more tech than they stole. For luke, he should be the only one that could possibly not die. But if he could there could be a death star trench run researched attack (think Rebellion) that you can send any squadron at the death star. If you think about it the only reason Luke destoryed the death star is because Obi-wan died. If Obi-wan doesn't die you shouldn't be able to destroy the Death Star. As for the Emperor and Mon Mothma what is the point of having both have the same power? Both sides are still in the exact same situation. Being able to kill one of them would give your side the advantage in the game. So 1) You are exhausting your forces to kill that hero 2) You are defending your hero like hell.