While the precise answer is not known for certain, wolf ancestry probably has much to do with it. Ancient breeds, including the Siberian Husky, possess DNA more closely resembling a wolf's DNA than do other breeds. Howling really boils down to communication, the main type being pack identification. In the wild this amounts to gathering the pack together again following a hunt. Wolves who do not go along on the hunt will howl to remind the others in the pack where to find home base again. And if you've been away from home all day, your domesticated husky may do the same. Howling may also be an expression of anxiety and thus an excellent attention-getting strategy, and a primal response to certain stimuli, including the distant sound of approaching sirens.
Yes. Huskies are adaptable dogs, able to flourish in any environment. Be advised that it's a bit more challenging for a husky who has been raised in a cold climate to move to a hot climate. The key to keeping this double-coated northern breed safe in the heat is plenty of access to shade, shelter, and water. Shaving a Siberian Husky who lives in a warm climate is not recommended, because the same undercoat that insulates her from the cold also insulates her from the heat: removing this protective layer can lead to sunburn and actually increases the risk of heat exhaustion.
The Siberian Husky frequently appears on top five and top ten lists of most dangerous dog breeds, with reported dog bites the oft-quoted metric. But many dog breeds—large and small—are capable of biting and aggression. Huskies possess an allure that draws people to them, including uninitiated dog owners who may not understand the commitment of time and energy that is part and parcel of Siberian Husky ownership. For this reason, the husky is well represented in animal shelters. But a well socialized, obedience trained, and supervised husky is not typically an aggressive or dangerous dog.
The scientific name for this phenomenon is heterochromia iridis, and it can occur in any dog breed, and even in people. The substance that gives the iris of the eye its color—melanin—is excessive or lacking in one eye. The condition may be congenital, or develops over time. And while genetics may explain it, heterochromia iridis can also result from an injury. It has no adverse effect on the dog's vision. And while it is more common in some breeds, including the husky, it disqualifies all breeds except the husky in most show rings.
In a word, yes: Siberian Huskies were developed to run and to pull, and if you've ever had a husky you may have found it difficult to train her not to pull—vigorously—against her leash. In fact, when she feels resistance, she'll likely pull harder still. Dogs on sled teams grow more and more excited and impatient to go while they're being harnessed, falling silent only when the sled is finally underway, content to do their work. But there are responsible and irresponsible dogsled operators as there are reputable and disreputable dog breeders. The best operators love their dogs and take exceptional care of them, feeding them the highest quality food, attending to their health and grooming needs in agonizing detail, keeping the kennels spotless, and giving the dogs plenty of time to play and socialize in a large outdoor enclosure—and usually also within the fold of the family who runs the operation. Your companion Siberian Husky may not actually pull a sled, but she is made for it and probably wouldn't object given the chance.