Welcome to canreef! And good by to your wallet in this planning stage
In terms of fish, if you can find a pair of midas bennies already paired, that's a great idea. But since it's nearly impossible to sex them, trying to pair them on your own would end in disaster. You'd have to look long and hard for a pair.
As for ventralis anthias... Unless you are very experience with anthias I would highly recommend staying away from these guys until you're ready. Normally I encourage people to try new fish and ideas but this is one fish this is a real challenge. First, they're incredibly expensive. Second, they're a deep water fish and often suffer from decompression issues, so they don't last long. Third, because they're a deep water fish they like dark, deep water style tanks. Most deep water anthias can be acclimated to brighter tanks, this one, however, doesn't acclimate as readily and will be stressed. Finally, they ar a finicky eater in every sense of the word... That is if you even get them to take a nibble.
For less troublesome but equally beautiful anthias, check out the Pseudanthias resplendens, Pseudanthias parvirostris, Nemanthias carberryi, pseudanthias evansi, pseudanthias Lori and Pseudanthias bartlettorum. Because of the size of your tank you may be able to keep a small schooling harem of anthias. I would recommend the Carberryi, Evansi or resplendens for this as they're most peaceful. Bartletts are hardy as heck but in a harem they may all try to kill each other to reach the top of the pecking order (bartletts have a propensity to change into males and challenge the top male). Something interesting to note is that Midas blennies will school with the anthias species I mentioned. If you want a fish a bit more challenging with similar behavior to the ventralis, look at the Fathead/Sunburst Anthias.
As for tangs, you could probably keep the yellow and the purple but stay away from the nasos. They're a big fish that only keepgetting bigger and bigger. They need length more than just volume. Be careful mentioning the Tangword arou d these parts.
One thing you didn't mention is the style of tank: fish only? Soft corals? Lps? SPS? Your equipment requirements will change depending on the livestock you are planning for