when obito lays down on juubi after coming from other dimension,he is so much wounded by kakashi + Minato ...juubi itself contolling him...obito lost concsiousness and he havent a control on juubi...
juubi is after naruto because he is seeing SO6p and tailed beast chakra in naruto.
i think that obito didnt do anything to become juubi jinchuriki its the juubi who used him to stable its attacks :D
Madara is going use perfect susanoo .
but i dont know about madara's trump card