Welcome to the forum. Regarding the deformed ones - I wouldn't take them in if I were you - as you rightly observed, they may not survive and this is according to nature. The small but normal looking ones might be worth holding on to if you like. There are details in our care article on Gray Tree Frogs (linked on every page) on how to raise them.
Those frogs will indeed consider eating froglets. The adult female gray tree frog will consider eating them too. But the froglets will not hang around the pond once they metamorphose - they will leave as soon as it rains and not come back until they are old enough to breed.