A planted Discus tank is large order for a lot of us on this site. I would try just Discus first. Mature Discus are more forgiving than young ones and with youngsters, you run the risk of screwing them up before they even reach adulthood. Like JayC mentioned, water changes, water changes, and more water changes, plus good high protein food for juvies. It will get hard worrying about your plants when you're draining the tank every other day or every day.
When you buy them, like JayC said, groups of around 6, like sizes, purchased from a reputable DISCUS source. Try to keep things as clean and as simple as possible while beginning. Go with domestic strains, so more than likely your tap water will be fine, may have to age your tap, and understand your Discus' appearance is directly related to your water quality,(assuming the genes are there) at least that's what I'm finding out.
If you're sure you want to start with young ones, 4" or less, I'd start them in a smaller bare bottom tank. Also I've found while keeping juvies, I don't need such a crazy filter bc I'm changing the water every day. Right now I'm keeping 9 juvies in a 60 gallon bb tank. 1 sponge filter and an AC 110. After a WC, I feed quality flake
and pellet 1 day, beefheart, blood worms, and another 95% WC the next. Keep a prefilter on, I found you are able to see exactly where the food goes so there should no serious overfeeding, and keeping junk out of the filter keeps your water quality up. I haven't had my fish very long, but hope this helps
