Yay, new aussie (or soon to be) hermit crab owner!

Don't get that PLEASE! Get the 2.5 foot tank, you could house 2-5 hermies in there instead on cramming 2 in that small kit!
Don't use "hermit crab salt" or any salt that is made for hermit crabs in general, these don't have the trace elements that they need, plus most of the time it is just rock salt that you get in the super market inside a package labelled "hermit crab salt".
Most of the time, bathing is stressful for hermit crabs, it better to provide dishes in the tank were they can do it themselves. and water dish they come in contact, make sure sure that there is no chlorine and other "product" that humans have placed with the water.
I hope the best for you

246L/65G - 'Tidal Jungle' (Crabs) | 246L/65g - 'Backwater Pool' (Fish/Snails) | 96L/25G - ''Twisted Minds" (Fish/Snails/Shrimp) | 300L/90G Fancy Pond (Goldfish)
I've never had any problems with 'Impulse Buying'. They're just animals that I forgot I had planned to get.