Dude, that's the definition of stray. No, srsly, cats don't need much training, and if it's really young, it's probably naturally overly trusting of humans.
And quit feeding it milk, it's probably lactose intolerant, and all the mewling means, "I have a tummy ache!"
And congrats! Kittens are cute. If only they'd stay that way...
And if anyone should name their cat, "buyer's remorse" (aka Babu), you should. (In honor of the most recent episode of Archer on Hulu.)