I think they have special paper you can buy for on the bottom of the cage. You can also use plain newspaper. They eat parakeet food that you can get at the pet store. It's seeds and stuff specially made for parakeets. I don't know if they are hypoallergenic.
They are NOT hypoallergenic. My parents had several as pets for over 10 years, & my dad developed serious health problems from living with them. They had to find other homes for them & completely redo their house top to bottom. He's much better a year & a half later.
You can use newspaper or paper purchased from a pet store for the bottom of the cage and they aren't hypoallergenic. they eat seeds etc. you can obtain at the pet store in addition to vitamins, cuttle bone etc. ?'s pet store, other owners or vet.