i used to keep rats. you might want to buy some rat food made for rats. maybe just a small bag because dog food has way too much protein for the rat. carrots are fine. is it cold outside during the night where you live? if its too cold, you might want to keep him in the garage. rats acutally do not smell so keeping it indoors would be most ideal. newspaper is fine. make sure there is plenty of water. as far as being male or female, males will have pronounce testicles under the tail. just watch him/her for a few minutes and if you see testicles, its male. if not, female. i am actually thinking about breeding rats to save money constantly buying rats. so that might be an option for you too. good luck.