I don't know if you are talking about breeder boxes like a Marina L.
But if you are....
1. It pumps air into an intake which forces water up, you get a lot of gurgly bubble noise
2. Shrimp babies should be fine, but new babies in a new box may be a bad thing since it doesn't have a lot of biofilm. I usually throw in moss and a layer of substrate to increase the chances of survival. ALSO the outflow's factory covers are usually too big and the babies escape so you may have to use a piece of ss mesh.
3. I would imagine you don't have to clean the box as long as you don't overfeed. I just leave mine as is with the condition of it having good flow. Continue reading for good flow options
4. I don't use an airpump. I bought an elite mini which I attached over the intake pipe for the marina breeder box. A better flow of water for better box circulation. I notice the shrimp like this more.
5. You could include a snail, snails hitch rides in my moss so I have them whether I want to or not.
6. Not really, personally I don't think the air pump is enough so I go with a mini pump.
7. If you have moss then once every 3 days? They like to feast on biofilm so yeah....you could use baby food, I would dose once every 3 days
8. I use Ebi Ken EI. Could use borneo wild bebi or something. Powdery would be the right complexion for the food since they are small and all that.
Hope this helps!