In what state are you located? State laws vary. For the most part, it should be legal to adopt them out.
Don't expect them to eat for the first day or two or even three. It takes some a little longer to acclimate than others. Just make sure you have a basking spot where they can haul out and get some heat and UVB light. You can start offering greens immediately, although some hatchlings won't eat greens for a few months. Do not offer processed or raw meats - not good. You can try cooked chicken or shrimp/krill (small pieces can be microwaved in a cup with a little water) just to get them started. Frozen blood worms (the kind sold for fish) or even live blood worms or small pieces of earthworms, if your pet store has them, are often accepted before other foods. Small crickets are another good starter food.
I HIGHLY recommend artificial or live plants for hiding spots. Hiding spots are so beneficial to a turtle's psychological health, especially to a juvenile. An exposed hatchling is a stressed hatchling, and stress can lead to illness. You can buy artificial silk plants at most dollar stores as well as Wal-Mart - cheap but very beneficial. Just throw them in the water, and the hatchlings will climb all over them.
A good book to have on hand is The General Care and Maintenance of Red-Eared Sliders by Philippe de Vosjoli from Advanced Vivarium Systems, Santee, CA (1992), available in most pet stores or Amazon.com
The following websites are good, too:
http://members.tripod.com/~Draybar/draybarturtles.html has some great ideas for aquariums.
http://www.chelonia.org/Articles/basiccarebasking.htm
http://www.chelonia.org/Articles/chrysemyscare.htm
http://www.turtlepuddle.org
http://www.angelfire.com/il3/janice/pondconstruction/construction.html shows how to build a pond and has links to ponding sites, should an adopter be interested in building a pond once the turtles are grown.
Katrina