Substrate is Eco Earth, roughly 6" deep, which is 2x my largest crab's height, maybe 3x with some generous estimates.
Fluker's Hermit Crab thermometer/hydrometer typically reads 80%+ humidity and almost always 80 degrees. A 40 watt lamp provides extra heat when needed, but the room is usually 80 degrees.
Fresh and Salt water are provided in two 1" deep pools roughly 3"x2" in dimensions. Water is treated with Zilla Water Conditioner, which says it neutralizes chlorine, chloramines and heavy metals and detoxifies ammonia. Salt is Instant Ocean, mixed as directed by the box with 1/2 cup per gallon.
Food is changed every other day and usually includes dried shrimp, dried coconut, fish flakes, crackers, lettuce and plain fruits and meats when I can get them. Tank is resupplied with water and old food is removed at this time as well.
All crabs are Caribbean PPs, four in total. One is moderately large, one is medium and two are small. The habitat is a fifteen gallon Aqueon fish aquarium. Eleven Turbo shells are provided, some gold mouthed, some silver. Each crab has at least 3 shells of their size to choose from. Three natural sea sponges about 1" cubed in size are placed in a small water dish and microwaved biweekly for cleaning.
Habitat has two cork logs, a small fake plant, various rocks and moss. As shown:
Depth (black bottom piece is almost exactly 1" tall for scale):

Water, moss and fake plant:

Shells piled next to cork log:

Sponges to the left, lettuce in center and crabs currently hiding in their favorite log:

That covers pretty much everything. I spent quite a while researching and shopping around to get the best products and keep my little colony happy.