Yes.
Maybe
No, gnat infestations generally do not kill indoor apple tree saplings. They are just fungus gnats from the soil as a result of overwatering. Cutting back on watering amounts and times should make the fungus gnats die off.
They weaken plants by sucking nutrients from leaves. Their worm stage will destroy young plants and cuttings roots, and will kill the young plants.
Potting mix does not kill earthworms.
I'm not sure if it will kill gnats, but there's a good chance that it will kill your plant.
No.
Fungus does not kill pesticides, pesticides (fungicide to be exact) kill fungus.
It depends on what kind of bugs you are trying to kill. Soap and water works well on most soft bodied insects. For example spidermites, and fungus gnats.
Yes, bleach will kill fungus.
Baking soda, also known as sodium bicarbonate, does an efficient job of killing mushrooms. When combined with a small amount of water, the baking soda forms a chemical reaction that is a fungicide and dissolves the roots of the fungus.
No. Wash the lining, use a spray that will kill the fungus, or wash the shoe.