So far in this thread, the most important factor in stocking a tank has not even been mentioned. Many aquarists get hung up on numbers vs tank size, but this is not the most important aspect because it completely ignores the needs of the fish species.
All fish listed in post #1 are shoaling species. That means they need a decent-sized group, and 10 of each species would be minimum. There are scientific studies now that prove beyond any doubt that a group of ten will be less stressed than a group of five or six, less aggressive, and feed better. This shows that the number of fish in the species group does make a huge difference. And this translates into healthier fish, which means less of an impact on the biological system. So more fish actually means less negative impact.
When considering fish for a tank, keep this necessity in mind, and make sure you have enough of one species before considering another species, and so on. A group of 10 neons, 10 cherry barbs, 12 embers (these are much better with more), and 9-10 cories. This is absolute minimum if you want these fish to be healthy and well-balanced. Weekly water changes, plus your live plants, and not overfeeding 2ill allow you to provide this essential environment for the fish.