Himi is a rather odd gene. It occurs in the C series, where some of the genes behave a bit differently, depending on what they are paired with. It is true that some Himis carry REW. Usually, you can tell if they do, because the nose markings will be smaller on one that is chc than on one that has 2 copies of the Himi gene (chch). Himi is also temperature dependent. During the hot summer months, even Himis that have 2 Himi genes will often have little more than just the end of the nose colored. Himi kits that get chilled will often develop dark pigment in the part of the hair that was growing at that time, resulting in ticking that will shed out with the next molt.
As to the question of whether they will be dwarfs or not - they will all be pedigreed Netherland Dwarfs, though some may not be of showable size. Most small rabbit breeds depend on the dwarfing gene to achieve the compact animals described in the breed standard. The dwarfing gene is a dominant gene, which means if a rabbit inherits it, you will see the effects of it in the rabbit. A rabbit with the dwarfing gene has shorter limbs, a shorter back, a shorter, rounder head, and shorter ears. A Netherland Dwarf without the dwarfing gene is slightly longer in the body and limbs, has slightly longer ears, and a slightly longer, narrower head. Netherland Dwarfs without the dwarfing gene are sometimes called "false dwarfs", and usually weigh 1/2 pound to 1 pound more than Dwarfs that did get the dwarfing gene.
The problem with the dwarfing gene, is that it is a lethal gene. One copy of it, and one copy of the normal growth gene, gets you the compact animal that can be registered and shown. Two copies of the dwarfing gene results in what a lot of breeders call a 'peanut.' Peanuts are only about 2/3 the size of their normal siblings. They typically have oddly shaped heads and weak, underdeveloped hindquarters. Peanuts usually do not survive more than 3 days due to their incomplete digestive systems, though I had one last 10 days before it died.
Obviously, since every baby that inherits two copies of the dwarfing gene dies within days of birth, you can't breed rabbits that are "pure" for the gene. Every Dwarf that meets the breed standard has one copy of the dwarfing gene, and one copy of the normal growth gene. Breed two of these rabbits together, and you will get some that get the dwarfing gene from either their mother or their father, and a copy of the normal growth gene from the other parent. Those are your "true dwarfs" that will most likely weigh less than 2 1/2 pounds when full grown. Some will get the dwarfing gene from both parents, those are the "peanuts"; they will die within days of birth. Some will get the normal growth gene from both parents. These are the "false dwarfs" that may wind up weighing as much as 3 1/2 pounds at maturity. False dwarf does are sometimes called "brood does" by breeders. Being slightly larger, they almost never have kindling problems, and often have larger litters than their true dwarf counterparts. Also, since they don't have a dwarfing gene, they can't give one to their offspring, so they never give birth to peanuts. Most people don't keep false dwarf bucks, since they can only be bred to true dwarf does and are too big to be shown.
