Room temperature is best (around 74*F/23*C). I tired to keep mine out of air conditioned rooms, but away from direct heat. If you want to know more about how to care for hermit crabs, go to hermit-crabs.com.
You Can but there's a water shack in hermit crab the keep the moister-ed and by washing them can destroy it
Sand, or fine gravel on the bottom of an aquarium, or a screen cage is ideal. You need to keep the cage temperature at least at 72 degrees Fahrenheit. The humidity level is best a 70%. The habitat for you hermit crab should have a moist warm feel, this will keep the gills of the hermit crab in check. Keep a spray bottle of fresh water handy and periodically spray your hermit crab habitat with it.
yes
If you keep them in a cold enclosure then they will die and you don't want that you need to put a heat pad then plug it in then check it daily.
no we had over ten hermit crabs in one cage and they were all fine.:) since they are both different sizes you should keep an eye on them but you shouldn't worry because hermit crabs are very social animals.
a small cage, like a plastic fish tank with rocks
it depends how big it will get
It's not recommended to keep different animals together, especially when they have such specific needs as a hermit crab (terrestrial). You can keep roly-poly bugs, or other species of hermit crabs safely.
if it is dead keep it if not still if it molted still keep it
You can convince your mother by doing chores and letting her know that you will be responsible for the hermit crab.
Hermit crabs do not eat people so you have nothing to worry about!! They mainly eat fruits and vegetables. Ask "What do hermit crabs eat" for answers on what they eat.
Spray it's crabitiat (habitiat) with distilled or spring water once a day. LIGHTLY spray the hermit crab not so much that it's dripping wet. so the same with the inside of the comtainer. you should also keep a couple sea sponges in the water dishes.