i had about 2 dozen baby turtles in a 30 breeder for a while. i use whisper filters and they are great filters for turtles. my whisper 5 keeps my 40 breeder crystal clear and there are 2 4.5" turtles and 4 4" turtles in there. it kept it just as clean when the 4.5" snapper was in there as well. with whisepr filters you should be fine. i always use gravel, it is natural for them to dig through it looking for food, so i let them do as they would in the wild since it has never given mine any problems. a big female RES could max out at over a foot. feeding in a separate container can cause enough stress to stop them from eating, and they are going to poop in their regular tank anyways, so i dont see the point in stressing them to feed them just so you dont have to clean their filter quite as often. they are more comfortable in their home, not in some sterile feeding enclosure. i also dont think they should be handled more than absolutely necessary, that means just enough to move them if needed to clean their tank, or check for illnesses, injuries, and that sort of stuff. 20long is a decent start for 5 baby RES, but you should start looking now for a bigger tank so you know what you are getting into, as well as how much you need to save for it. you will also need a proper diet, full spectrum UVB lighting, heat lamp, and a good book. if you have any other questions please ask them, i dont know about everyone else, but i would rather answer 100 overly simple or "stupid" questions than read one post about a sick turtle.