Hello Kean and Welcome to Simply!!! I'm not sure you need much help because you've done a lot of research and have already set yourself up for success!!
As far as food goes, if you do a search the forum for beef heart recipes you will find some great ideas and many people use BH as one of the main foods for discus. I'm not sure of the availability in S. Africa, but freeze dried black worms are an excellent source of nutrition as well. If you plan to feed live foods, do some research on the source and make sure it comes from a clean and disease/parasite free environment, and NEVER feed tubifex worms. I also feed mine Tetra Color Granules as a dry staple, but other dry foods are available as well. I feed them granules as opposed to flakes because discus like to peck for food along the bottom of the tank.
Again, I'm not sure of the availability in S. Africa, but as a beginner I would suggest you keep metronidazole, praziquantel and possibly levamisole on hand. If these aren't available over the counter you may check with a veterinarian.
If you ever add to your collection, make sure you have quarantine tanks to condition your new ones.
Good luck, ask questions and give us update on your project!!!
Brian