You're going with a 75G, right? That should be fine.
All of these fish are pretty small. If I were you, I'd stick with the larger bicolor or go with one tang ... something so that you have differential size ... nicer for viewing. 75G tank is large enough to have one decent sized fish. In mine, I have at the moment 1 large salfin tang, 3 green chromis (2 perished -- I had 5), 2 small percula clowns, 1 royal gramma, and one lawnmower blenny. Gonna probably add 1 atlantic pygmy angel and/or a yellowhead wrasse or cleaner goby.
No point to adding 1 hermit crab. First you need to decide, live rock? Sandbed? Both? If to you go with either, you need a cleanup crew that is roughly equal to the number of gallons of water in the tank. So we're talking somewhere in the neighborhood of 60 critters (remember, rock/sand will displace some water so you won't in fact have 75G.) Many places sell packages, or you can find folks on reefcentral.com selling lots of them. Even ebay.
Nassarius snails sift sand and eat the garbage. Of course, mine don't go near the sand they stay on the glass
so my sand looks like hell
Cerith snails are supposed to eat lots of nasty algae and stir the sand.
Nerite snails eat all sorts of algae.
Turbos (Astreas are supposed to be the best, I have none) are allegedly the best algae cleaners. I'm out to get some soon.
Crabs: mine eat my snails and I don't like that. Others have had similar problems and have had to decide between them and snails. But most places combine them in packages so I have no idea what the norm is.
Emerald crabs are great hair algae eaters and will wipe out bubble algae (never had it, supposed to be a real drag so worth having one in the tank).
Red, blue, or black and white hermits all have virtues. I find them all to be murderous.
The right-handed hermits are definitely psychotic.
So decide and get a bunch.
OH -- I would definitely at least have live rock in the tank. It is pretty, it is a natural filter, will keep the water clean, and will be interesting to watch. You can do this cheaply, too. Get a bunch of dead, dry base rock. Again, look on reefcentral for someone in your area getting out of the hobby, or just search around for baserock. It's cheap, dry rubble. But you can't use just any rock. Had to at one time have been live.
Then add 2-3 pieces of live rock -- either buy them from a store or find someone to give you a couple or buy them from someone. The corralline algae will spread fast, the critters will multiply, and you'll have a really interesting tank.