"The baby washes"
No. Because there's no context, we don't know what the baby washes and which verb should be used. Anaoga would mean the baby has a shower or bath, washes his/her whole body whereas ananawa would be used if the baby washes his/her face or hands, a specific body part, I guess.
As I've said before, what I dislike most about this course is not the bad English and lack of alternative answers, but the complete lack of context. We would pretty much never say "The baby washes" in English ... it needs more context, so what is the point of this? It's like asking us to translate "I always put" ... put what where?
I found something Look at this. I can't link it in here. type Amazon swahili literature & fiction books into Google. You might not want to buy the books but if you click on each book there is on the book picture a look inside link which gives you quite a few pages of the book. For language learning this might be sufficient.
No, unfortunately. There must be some but I don't know how to search for them.
I read news articles on http://www.bbc.com/swahili
And I also google phrases that I come across in the translations at https://glosbe.com/sw/en/ to find the original article. It's really only the Jehovah's Witnesses and occasionally a website called Global Voices that are there. The JWs put out their magazine once a month and they write about a range of really interesting topics. Of course, whenever they talk about animals, it's not long before I'm rolling my eyes as they pretend to have valid criticisms of science, and I find a lot of their other attitudes pretty disturbing, but the range of topics is pretty broad and the standard of translation seems to be quite good. With both JW.org and bbc Swahili, you can also find the same article in English to check how well you understood.
kufua nguo - to wash (lit. "beat") clothes / do laundry kuosha - to wash (something/someone else, like a baby) (kuosha vyombo - do the dishes) kuoga - to wash/bathe/shower kunawa - to wash a certain body part; usually the hands, face or feet (originally in a religious context)