They love watermelon! It is fine to give it t them now, just be car ful f the seeds. They will eat almost anything
But it n my extra eerie century don't like blueberries, avacados or potatoes.
Okay, well looks like you are on the right track. I have no experience with antibiotics, so you should wait for someone else to come along. Congratulations again on your new brood!
Antibiotics really ar it neccesary. It is correct, if your chicks are sleeping farther from the light you should raise the light higher above. Looking not at the pictures of your brooder, I would recommend covering the newspaper with a different bedding. It is recommended to only use newspaper...
Could your Black chick be a Dark Brahma? Ridge runner gave you some much excellent advice, but I would like to add on and say that. Occasionally, the mother will get off her nest while the last egg is still hatching. Thos has happened several times. We take the hatched chicks inside for a while...
To add to what Ridgerunner said, you should make sure your bedding is easily cleaned and you have a good supply of it. It shouldn't be too hard, but not soft enough that the chicks can't walk on it. It needs to be able to support food and water containers so that they don't fall over.
You may want to check out this article: http://modernfarmer.com/2016/03/how-to-raise-chickens/ I don't think it has the answers to everything you seek, but it has some good advice. Antibiotics and vitamins are not required, but once they start to lay you should definitely give them the egg...
I do not give medication to my birds either, but you might want to give them some kind of chick friendly grit, for their digestive system. For the first 2-3 days you may want to put a VERY TINY amount of table sugar in their water (Myer hatchery recommends about three tablespoons in every...