Sounds like a great plan. Here are some suggestions:
live sand vs. aragonite - Well, all sand once established in a reef tank will become live sand, regardless of what it is to begin with. If you are referring to the prepackaged "arag-alive" or similar live sand, save your money. You are better off buying dead, dry sand and letting the live rock seed it, or seeding it with a few pounds of real live sand from a tank at your LFS. The grain size of sand and depth of the sand bed are a largely disputed topic. Try searching this site and you will find numerous threads on sand beds. Just to sum it up, though, fine, sugar grain sand is better for deep sand beds. Crushed coral is better when used very sparingly, like just enough to cover the bottom glass. Crushed coral needs to be siphoned during water changes to keep it clean, so having a thin layer makes this much easier.
Your fish list sounds perfect. I would suggest getting tank raised ocellaris clowns if you can. They are much stronger and hardier, are used to human contact, and of course are more eco-friendly.
Hermit crabs - Some people like hermits, some hate them. Just be aware that crabs by nature are opportunistic feeders. If they have to, they will kill other animals in the tank to eat or to take their shells. Most people agree that scarlet hermit crabs are the safest.
Sally or Emerald crab - Again, crabs can be trouble. Sally lightfoot I would avoid at all costs. They can get huge, and they can be aggressive. I would go with either one small emerald crab, or no crab at all. Even emerald crabs are sometimes bad.
Snails - Most snails you see in the LFS or online are fine. People tend to get a mix of snails to clean the glass, rocks, and sand. Astraeas, turbos, and margaritas are good for the glass and rocks. Nassarius, ceriths, bumblebees, and conchs are good for the sand. Get a few of each, and if your algae is still out of control add a few more. I wouldn't put more than 2 turbos in that tank, though, as they are big.
Starfish - Not a good idea. Starfish are never recommended for beginners, and never recommended for new tanks. So that's already 2 strikes against you. Starfish are very fragile and the slightest change in salinity, pH, or other parameters of your water can kill them. Most starfish get fairly large and in a small tank like that they can run out of food or knock things over. If you get a starfish, you get it at your own risk.
Featherdusters - These are great and fairly low maintenance. If you get good live rock you will probably get some small ones as hitchhikers. If you buy some of the bigger ones, remember they are filter feeders so don't get too many for your small tank.
Corals - All of those corals will be great for that tank. Once get get more experience and your tank is more stable you could even get some LPS corals with that amount of light.
I hope this helps and good luck
