what i have found with my clowns is that they are pretty forgiving about water parameters as long as it stays consistent. the stuff on the internet about needing zero hardness and really low Ph hasn't held up. mine breed consistently in hard, neutral Ph water. just be sure to keep it clean and stable, and as always drip acclimate them (maybe even a little slower than normal).
they can be pretty picky about food, but i was able to train mine to eat flakes. they do seem much, much more excited when given live food though, so i would recommend mixing it in sometimes. daphnia particularly were a big hit. i also give mine frozen foods to add some variety and meat to their diet. the biggest thing about food is that whatever you give them needs to float. they don't gorge themselves like tetras do, and need the food to stay on the top long enough for them to pick their way through it.
another tip: they need some sort of floating plant to feel secure and for breeding success. i've found that without floating plants none of the fry survive long.
the term "hardiness" is pretty subjective. these fish do seem a bit more delicate than your average tetra or danio, but really all they require is smart fish keeping.
1 A. Borellii
10 black neons
1 dwarf gourami
2 otocinclus catfish
+ about a million snails
17? clown killies
unknown # of RCS
+ about a half a million snails ;)
6 gardneri n'sukka killies
+/- some fry