Leave them in the fridge if it's an option, otherwise they should be fine with that and food scraps. The newspaper is there to keep the soil moist, and the soil must stay moist or the worms perish. I haven't found a way to remix the soil once worms are in, I'm confident the best way would be to replace dry soil with damp soil and that would be a big pain. The worms could potentially reproduce, I think 600 will last you a while if you get them onto frozen. If you see ANY dead worms remove them, they will mold over or something and the rest of the worms will die. Keeping them covered in the fridge is your best bet, it will keep you from having to do almost any work. (you will appreciate this after dealing with worms for a bit) Once onto worms I found it easy to get my rays on to frozen, evenwith hystrix being somewhat picky I think you won't have trouble with that pair. If they are already eating wait until they compete heavily, look for signs of one pinning the other to get its food. Once they get into food frenzy mode they will take/chew/taste to just about anything fleshy.
