i have a 40 g tank with 4 discus. i do a 50% water change every other day, and feed them blood worms and they are fine. Add some driftwood to your tank to soften the water, and make sure the temp is 86 degrees...about. if you want them to lay some eggs have a flat rock. Also, discus like to hide a little sometimes, so try to get like a cave...or just make one! Also, try to get discus in pairs, even numbers and discus certainly mix well!
and despite the fact they're small now, they're going to need a larger tank asap. I mean i know mines still a bit small but i'm working on that ;]
thats all my advice to you, as for the pecking thing, i dont know what to tell ya...maybe a hiding place for them will get them to calm down a bit.