Okay, mousey care... There's also a feeder food forum you can scan through, but here's some info. I kept mice as pets for a few years so may be able to help.
I kept them on pine shavings and they're happy on that, but you may want something more sterile for the sake of your snakes.
I fed them a deluxe type mixture of fancy grains, dried corn and even dried banana slices. Stuff almost nice enough to use as trail mix. You may be able to get cheaper stuff that'll work as well, but your mice are what they eat, and by extension so are your snakes.
Female mice smell a little mousey but male mice STINK!!! You need to change the entire cage regularly.
Mice are reasonably sociable critters, but you may want to house the males from females seperately most of the time, just to prevent random breeding. They can and will breed like rabbits. You also need to prevent them from getting overpopulated or they'll be stressed and beat the hell out of eachother.
Mice are escape artists. What they can't squeeze through, they can chew through. Well ventilated tupperware or breeding trays may work. They need fresh water, gentle temperatures and just to be nice, you can give some of your cages an excercise wheel (maybe not with the newborns but anywhere else).
Mice are incredibly simple to sex. Just lift the tail and look for a very prominent set of testicles. You may want to get all your males unrelated from your females. Also as soon as your baby mice are weaned, seperate the sexes to prevent pregnant mice at the pet store. (see below)
The suggestion to sell your extras to a petstore is a very good one. Here's how you can take it a step further. Get a very nice relationship with your pet store. Find breeder mice that are adorable, with good proportions (best you can tell anyway) and unique colorations, spots, hoods, stripes, etc. The mice you can sell to the petstore are the nicest female offspring (they're the best pets as they don't smell), and maybe a few males. Keep the least attractive (so long as they are healthy) for snake food. You can probably also exchange mice for mouse food at the store and get an exceptionally beneficial relationship going.
They're a fair amount of work, so I frankly recommend searching for bulk some more. About frosty mice, put the dead mice in a good ziploc bag to prevent frost and freezerburn. defrost your dead mouse in a bag to avoid water condensation on the mouse. Worst comes to worst, you can get a paper towel and dry your mousicle off.
My fingers are near falling off from typing, so I'll end here. Good luck!
P.S. If you can't find a bulk supplier in your country but find you like raising mice, you may be able to start a buisness monopoly! 
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0.2 chickens
0.2 dog mutts (half ownership, only mine when they misbehave)
0.1 Halflinger horse
0.0 reptiles due to living with
1.1 parents
Still searching for 1.0 WC human
