I see a few issues:
both apistos and rummynoses can be quite sensitive and I wouldn't put either into a new tank myself. Even if you've got media from another tank, I'd wait to make sure you've got your parameters stabilized before introducing either of those stocks.
I don't like lots of small groups of tetras, especially in a 55 where they will just disappear. I'd advocate going with one large or two semi-large groups of tetras. Rummynoses are lovely. I'd vote for them. A second one could be any number of types include von rios, embers, etc. I would not do neons personally.
I'd also not do 8 apistos. I've only ever done apistos in pairs, and sparingly. They can be nasty and territorial IMHO. I'd make two or three different "habitats" in your tank. use rocks, wood and plants to sort of separate the areas. I'd probably also only do two pairs, and I'd probably buy them as pairs.
I'd not do angels. I might do another low-key cichlid like keyholes or rainbows (yes, my two favorites)
any variety of medium light plants would be fine. get about 2 watts per gallon and use Excel regularly so you don't need Co2.
Eco complete works fine for a substrate for apistos IMHO. Sand is not necessary, although you could cut the eco complete with some sand if you wish.