mice love all treats. you can give peas, corn, well any veggie but pickles i've heard. (like i'd give them pickles anyways, they're MINE! lol). you can get those hamster yogurt drops, looove those! as for toys, anything goes! toilet paper tubes, paper towel tubes, any box from your recycle bin (like a crackers box, cereal box, pop case). apple tree chew sticks you can find at stores, they're good too. anything wood (not pine or cedar).
sometimes i run out of bedding, newspaper is a good sub but you have to change it more often. it's safe because nowadays the ink is all soy based.
the salt lick stone can stay in the cage until it's done, no need to remove. my rat (i know you have mice, same dif) has his attached to the side of the cage. it's just left there, in case he feels he needs it.
all the stuff about mite spray and shampoo you dont need to buy until it's needed. if you keep a clean home and cage, mites may not be an issue. and mice groom themselves so they don't need baths unless someone gets squidgy poo lol.
"If you can't change your fate, change your attitude." - Amy Tan