Congrats on the acquisitions.
Don't worry about the fish not feeding; newly acquired fish frequently won't show much interest in any food for sometimes a few days. Black Neon Tetra
will accept most prepared foods. Having said that, it is good to provide variety, say 3 or so different prepared foods (flakes in this case) made by different manufacturers. This way there is variety for the fish, plus probably some variance in nutritional properties of the different foods. Most contain the essentials, but some fish seem to prefer some foods over others.
On the plants: the sword you plant in the substrate (gravel, whatever), deep enough to cover all the roots, they have extensive root systems. The Anubias
you attach to rock or wood, don't bury the rhizome (root) in the substrate or it will rot. The other 3 I can't say, as I don't know what mystery plants they are
. A photo would help us there.
What light is over the tank? And do you have any liquid plant fertilizer? I can recommend some if not, you will need one.