discus come with the myth that they are hard to keep but with good tank maintenance and good filtration its no harder than any other fish tbh. they eat alot of meaty food and this is where the water quality can go down hill. this is why people keep them in bare bottom tanks so excess food and poo can be removed asap. they are also slow eaters that pick at food rather than stuffing their faces like most other fish. if you really want them then go for it, as long as the water params are stable it will be fine. i would suggest going for a large discus rather than a small cheaper specimin as they arent as fussy and can be fed just twice a day instead of up to 6 times a day for juvi discus. try and get some around the 5-6 inch mark and look for a local breeder or specialist discus seller rather than the lfs as they will be cheaper
angels and discus together looks amazing, if you can get it to work.... angels can carry some kind of disease that doesnt effect them but does effect discus, cant remember what it is off the top of my head but mixing the 2 species can be a risk.... if you do go for it then go for altum angels as they look amazing and much more elegant than scalare angels
cory and emperor tetras will be fine with both species, as long as the tetras arent tiny they should be fine.
i wouldnt add any bigger fish tbh as the discus can grow to the size of a small plate so eventually will fill the tank nicely with a group of them especially if you keep angels too. maybe a pair of german blue rams as these prefer the higher temps that discus need
just to add i kept my discus at 30 degrees in medium/hard tap water with a pH of about 7.8 without any disease or issues what so ever. just acclimatise them very slowly especially if there is a big distance between your pH and the sellers pH. take at least an hour to do each fish and they should be ok.
corys do generally prefer cooler temps of about 24 degrees but it is said that sterbai corys tolerate higher temps better than any other cory. having other corys in a higher temp tank may cause stress and make them quite inactive compared to normal. also the higher temps may reduce their life span. people do keep all sorts of corys in with discus at high temps and they will say they are fine but they do prefer cooler water
ive just finished my stocking plans for the tank you saw in my garage after going round in circle and down different routes and have come up with -
2 x asian sun catfish
1 x L190 pleco
1 x L114 pleco
3 x spotted climbing perch
1 x oscar
1 x siamese algae eater
1 x black ghost knife fish
1 x rotkeil severum
its a mix of fish from all over the world but this tank was never meant to be a biotope or species tank of any kind just a 'me' tank. they should all live together quite peacefully (i hope) and require similar water parameters and temp etc. just dont forget that discus, angels and other bigger species do and will get bigger than what you picture in your head. maybe try and personally go to look at some fully grown fish that you decide to go for to show their potential sizes. after seeing the oscar i have reserved i decided that i didnt want any other big cichlids in the tank as he is huge..... i was going to add a frontosa and a red spotted severum too but honestly think the tank isnt big enough and thats 6.5/2/2