make sure it's eating mice first! ask the dealer to feed it in front of you (offer to pay for the mouse). they can be tricky to start on mice if you're getting a baby that hasn't eaten yet.
venom is nothing; there was an experiment where it was tested against human saliva and saline solution. they all had about the same reaction in a human- local itching and minor swelling (wish i could find the link).
15 long is ok, 20 long is better.
needs a heating pad @ 90-95f on one end of the tank (no lights, they bother a lot of snakes i've noticed). **tank must be big enough for a temperature gradient and for it to get away from the heat**
2 hides, one moist (a tupperware container with a hole cut in top filled damp sphagnum moss or cypress mulch works best and inhibits mold growth) and one dry (flat stone or piece of cork bark).
a thick 3-4" layer of aspen shavings is the best substrate for these burrowers.
they might put up a noisy hissing fuss when 1st picked up but they almost never ever bite, ever! they do strike but they never open their mouth while doing it (it's a fake out). they calm down quick and easily and are a pleasure to handle. i have never observed a captive western feign death or bite, even when harassed (easterns are more prone to feign).
have fun, i love these guys!