Feeding night crawlers is easy, they eat whatever they live in pretty much. I keep mine in newspaper shreds that's damp and kept in the fridge and add organics in and lots of high calcium things, like eggshell bits, calcium enriched foods and bone meal. As for feeding them to your snakes, well Steve said it all. You can feed them within a few days I'm sure, I only use one worm per feeding, so most of them are in there for 1-6 weeks before being eaten.