As Minato had said, he didn't have the strength to seal away all of the Kyuubi with only the reaper's death seal into sucha young child. However Kushina and the other Jinchuriki have all been able to seal away their full chakra. The only reason Naruto didn't get the full sealing is because of the situation they were in during his birth. Other than that it is possible to confine the Kyuubi or any other tailed-beast within a person with it's full power.
As for the missing half, it's possible it can be resurrected as I believe a tailed-beast will regenerate after it's been destroyed after so long. It's also possible that they will have Minato's body and be able to extract the chakra from his remains.
However this is unlikely as he's already taken measures to ensure he has enough of it's chakra.
"By nightfall, Tobi arrived at the battlefield and took both the Benihisago and Kohaku no Jลhei, each containing one of the brothers inside, intending to use their Kurama chakra to help enact his Eye of the Moon Plan."
-Narutopedia