3) Rocks are safe as long as you really clean them before bringing them in. you don't want to bring any little insects along for the ride.

5)Using too big of a tank will cause issues if the snake feels unsafe. You can use that tank, just make sure to provide plenty of hiding places and objects to make it seem less open.

6)My understanding is that the petstore light is designed to throw off more heat than the walmart one. Most light bulbs are going for energy efficency, which means less heat.