And no, Minato did not seal Kurama's "soul" with the Shiki Fuujin, only the Yin part of its chakra, the mechanics are different with regards to Orochimaru's arms, Orochimaru's arms were the arms of a real soul, Kurama's Yin Half is just chakra, that is why the former (Oro's arms) could not be assimilated with Hiruzen's own soul since no two things can occupy the same space at the same time.
Kurama's Yin Chakra is just that, chakra, capable of being assimilated inside a soul. To further cement this, take a look at the difference in effects between Kurama's sealing and Oro's sealing, in Orochimaru's case, the use of ninjutsu requiring hand seals has been completely sealed away from him because the arm part of his soul was truly lost, while in Kurama's case, he is still able to use the techniques of Bijuus like Bijuudama, that is because only his Yin Chakra was missing, the only thing that was limited is the energy output of Kurama's Bijuudama since half of his chakra was taken away but none the less he was still capable of using it.
From this we can clearly see the substantial difference between Orochimaru's and Kurama's sealing with RDS, the former truly lost a part of his soul while the latter merely lost his chakra.