Welcome to TFF. There are many planted tank members here who will be able to answer your questions. First issue though, is the list of fish mentioned in post #1. A 40g tank is insufficient space for angelfish unless you have plans for a 6-foot or larger tank in the very near future. Zebra danios are very active swimming fish, and would not work with sedate angelfish. Corydoras are shoaling fish (as are tetras, danios, etc) that need a group, and in a 40g with a sand substrate you could have 12-25 or even more, depending upon other fish; cories are always healthier the more there are of them. But the first thing is to establish the water parameters (being the GH, KH, pH) of your source (tap) water. Selecting fish that will function best in your water will avoid a lot of problems going forward.