Make sure you drip acclimate your inverts for at least 2 hours, they are very intolerant of water changes.
I am not a big fan of hermits, I have 3 maybe 4 in my 55G. Make sure you get them some bigger shells to move into, otherwise they might make your snail's shells their homes. You can probably buy extra shells at a local craft store.
Crabs tend to become more agressive oince they get bigger, so I would only go with one emerald crab, or just pull that piece of rock out and clean off the algae.
You snail selection sounds good. Maybe look into a fighting conch.
The HOB, you can leave on and remove the sponge.
Does it have a biowheel? If so, they tend to become nitrAte factories and can be replaced with LR rubble.