I find it odd that Yasuke would be a Samurai, when Toyotomi Hideyoshi, one of the three unifiers and a general under Nobunaga, was not.

After unifying Japan in 1590, Toyotomi Hideyoshi did not become Shogun because he was born a peasant. Only Samurai could become Shogun, and Hideyoshi was famously not one. You couldn't become a samurai, you had to be born one.