Bridget to Morphun - Pillz are the most important thing in survivor, you don't really need more life since when you get in the later stages you will more often than not have more life than your opponent, but less pillz hence why Morphun is the most valuable leader of them all.
Stella to Uranus - Stella's 6 damage is not very impressive and all she is only useful for is walling, but most good survivor decks will just through a dr at her if they feel they can't afford to risk pilling against her, thus taking away her only real strong suit. Also Uranus is to invaluable since he can block up 5 damage with such a low minimum. There really is no reason not to run him. If you are worried about his offense, don't be because after playing with him for awhile you will not ever want to not play with out him, since he will save you from defeat more often than not.
Now for some strategy.
Double Olding is not always the answer. You have to pick and choose when you old because against good survivor decks and players, they will use that strategy against you by just 2 pilling and thus wasting your efforts. Before you old ask yourself a simple question. Can I afford to take this damage. If you can not afford to take this damage, then just old with you dr and live to fight another round, if otherwise, then try to predict how many pillz your oppenent will pill and pill accordingly. Please note that most good survivor players try to conserve pillz, so try not to over pill since more often