I'm all for hobbyists who can manage to keep and care for unique, larger and relatively rare fishes.
Were you referring to Ctenolucius hujeta
on your Barracudas? The good news for your Vampire Tetra is that the one you plan to obtain is a small one of their group ( about 16-18 inches). The bad news is that they still may not work well with the other fish you plan. More bad news....If the catfish doesn't get picked on, harassed, or killed by the other fish you plan to keep, it can grow to eat the other fish you plan to keep.
Plants could actually be relative, if you want to create a flooded portion of the Amazon considering that two of the fish species you plan to keep do not come from that region. In that respect, I would recommend a combination of a few different plants that can be planted in sand/gravel and some that can be attached a grown on the driftwood you will have in your tank. Java fern, Java Moss, or various Anubias (nana and barteri are good ones) that can be attached, then will grow on your driftwood (and rocks also). Other plantings, such as swords would also work, but may require more than the standard moderate lighting that would normally come with light hoods.
Either way, this sounds like a bold endeavor on your part. I would wish for you to succeed and let us know your progress on your tank(s).