It is always mentioned in the manga that kyuubi's power was controllable only by wood style or sharingan. But Uzumakis had developed the greatest of sealing techniques for kyuubi.. Din't they also control the kyuubi?
Also, since Minato knew about many of the Uzumaki sealing techs, couldnt he seal the kyuubi back in Kushina and even NAruto and have lived instead??
Did Minato want to die??
It's not really wood jutsu, it's an ability that Hashirama has that he uses with his wood jutsus. Yamato who is a watered down clone of Hashirama had the chakra come out his hands
You must be registered for see links
and
You must be registered for see links
. But yes, the sharingan and Hashirama both have the ability to control Bijuus, I think Hashirama's ability is stronger though since Orochimaru put it as Bijuus bending at his will plus he had most of the Bijuus
You must be registered for see links
.
The Uzumaki's way of controlling Kurama is to seal him away, only Naruto and maybe Mito used Kurama's power good enough to get at least KM. Obito mentioned how Mito could sense negative emotions which Naruto got in KM/BM/BSM. I'm pretty sure it wasn't known that you could save a Jinchuuriki or at least an Uzumaki one by resealing the Bijuu because Kushina said she would reseal Kurama to die with her but Minato said he couldn't let the 9 tails be later revived without a host since it could be disastrous and mess up the Bijuu power balance that the 1st Kage's created.
Since Naruto was only a baby, Minato didn't think he could handle all of Kurama's chakra so used the death repear seal to split it's chakra into yin and yang and seal them separately. It was Kurama who told Gaara that Naruto could still be saved if they make him a Jinchuuriki again so that info wasn't known by anyone but Kurama and maybe other Bijuus.
-Sealing something is different from controlling it.
-The rinnegan can also control the kyuubi
-Minato could have sealed the kyuubi back in kushina but she would have died. He wasn't sure naruto would be able to handle the full kyuubi so he split it in half using the reaper seal.
For the rinnegan part, Obito was using it to control the Jinchuuriki's body while having the actual Bijuu's chained up in the Jinchuuriki's innerspiritual place so we don't know if it can control a wild Bijuu like it can a sealed one. Naruto is being revived by becoming a Jinchuuriki again so I don't think she would have died but more of they didn't have that knowledge since it was Kurama who told Gaara it so either only Kurama knew about it or all of the Bijuus did.