If you never kept Discus before try to get some locally breed tank raised fish as opposed to wild cought unless they have already been acclamated to your local water, but I think you'll better off with at least F1 over F0. In my experiance Discus are no harder to care for than any other cichlid, keep the water warm and environment clean and you'll have no trouble keeping them. Personaly I'm not into bare bottom tanks and have always kept mine in planted tanks with pool filter sand as the substrate, however a nice set-up with drift wood looks good too. If you go with the drift wood subdued lighting such as a 10K fixture over the center of the tank (not running the full length, ie a 36" fixture over a 48" tank) with darker corners is a nice effect and reduces skittishness, also floating some frog bit, duck weed or water sprite will produce a similar effect if your light is strong and you don't want to change fixtures. Raising or growing out Discus in ultra clean bare bottom tanks with constant water changes does help them reach a larger size however I've always been happy with 5" or 6" display tank fish as opposed to 8" show specimens, so it has never been a major issue for me. I had one common pleco and several Ottos years ago that developed a taste for Discus slime they didn't last long after that started, so a word of caution on that subject. As far as water changes go 50% a week is fine more is better do 75% if you can. As for your Ph at 7.6 like I said if you get local fish they probibily come from the same water as yours so it wouln't matter but ask the vendor the water parameters they have been kept in. Once the fish are acclamated I would not mess with the chemisry, the water you use for water changes should be the same as the water in the tank and you'll have no issues. I hope this was helpfull.