Hmm, auteur theory is an interesting direction to go with Kurosawa. It absolutely fits, and there's a lot to write about there, and I can definitely see how there it would help to focus on more than one of his films, to demonstrate tendencies across his filmmaking.
There's a lot of interesting things to Kurosawa's films that lend themselves to auteur discussion. There are a lot of angles to take, such as his films' relationships with nature, or his portrayals of power dynamics, or perhaps a focus on the editing -- there's a lot going on there, and him editing his own films certainly lends itself to an argument for Kurosawa as auteur.
Definitely look into the autobiography I linked above, and this collection of interviews should help as well.
My paper, as I said before, was much more about Kurosawa's legacy and reception than his directing style itself or him as auteur, so if that's the angle you're taking -- which is a fine angle, of course! -- then there's less I can offer you in terms of my personal knowledge of Kurosawa.
I'd say it's still possible to focus on one film and how it is expressive of Kurosawa as auteur if you'd like, but for that particular topic, a more comprehensive look at his extensive body of work might be a good idea as well.
Edit: I should mention that my Bachelor's is actually in Anthropology, not Film, which is (partly) why I focus so much on and know much more about the cultural and historical context of Kurosawa and his body of work than I do his style of directing and him as an auteur. The paper I wrote was for a Film class, but I personally have much more of what you might call an Anthropology background than a Film one.