Dear forumers, I need urgent advice!

My sis just brought (Not bought) home a kitten, well... The kitten was actually just outside our home, on the roadside But anyway, it was late at night when she brought it in, my mom gave him/her (I dunno how to check) warm milk as the kitten look really tired/energyless/something like that, and a box, newspapers and towel for the night. Then, this morning, the cat got milk for breakfast and tuna for lunch.

My question is, what do/can kittens eat (Or cannot eat)? Can it take a bath (Kinda dirty)?

Thanks

Okie, thanks... Will pass on your advice to my mom and sis So, they can only eat cat food?