If you live in a very hard water area you might want to reconsider all of those tetras... they are softwater species. How hard is it? You can buy reverse osmosis filters which produce very pure water, and mixing 50/50 RO water with tap water often provides a suitable medium. Most farmed tetras for the aquarium trade are okay with medium hard water (in the wild their water is almost zero hardness) but may not thrive in very hard water. It's complicated but basically hard water allows more bacteria to survive so they often become extremely prone to illness. They will certainly not breed in hard water.
If you don't want to go for RO and your hardness is more than 200-250ppm, you might want to consider getting more livebearers and possibly rainbowfish, as they are hard water species.
Bristlenoses would be ideal, they are peaceful and do not grow large for plecs, only about 12-15cm (males at the bigger end of this range). You could have three in that tank but I wouldn't put any more in as they can be territorial, especially if you have a mix of males or females. My LFS has a four foot display tank with three fully grown males in it and they never fight at all, but if a female was present it might be a different story. If you can get BNs that are old enough to sex, getting all the same sex might be a good idea.
Definitely get only male livebearers. If you buy female platys that have been in a tank with males, they can store enough sperm for six to eight pregnancies. So with six platys, you could end up with 180 fry a month for the next six to eight months, and that's based on 30 fry per platy per month which is a low estimate.
If you combine male guppies with tetras, sometimes the tetras like to nip the long fins of the guppies. This can be reduced or prevented by choosing less nippy tetra species (which you've already done; the really bad nippers like black widows are not compatible with guppies) and by choosing male guppies with smaller tails. Males with large tails are slower swimmers because of the weight of their tail and the drag it produces, so if the tetras do nip them they can't get away - males with smaller tails can usually evade the tetras even if they do get nipped.
If you want corys and bristlenoses you should avoid using a very sharp substrate, but sand, coloured gravel or pea gravel (small, rounded pebbles) are all fine - most substrates are, but if you run your hand over it and it feels sharp you should reconsider. It can damge the corydoras' barbels and the bristlenoses' undersides.
As for stocking, if you choose to fish in cycle I'd add the danios first and then the platys. This should be enough fish to establish your bacterial population. Then you add the other fish slowly (two or three a week) and this will generate only a very small spike, as the bacteria are already there and need only multiply to deal with the added fish. Your tank can support everything on that list. It sounds like a very nice community actually, and Mopani wood is gorgeous... put up some pics when it's all set up, I bet it's beautiful!!!
