That's why bears are ambush predators, they are unable to keep up the chase for very long but are fast enough to get you at the start. I have seen footage of wolves literally running for miles and miles in chase of prey but I agree that werebears will be / should be just a little bit slower then werewolves but the power possessed by the werebear ought to be profound to make up for their slow movement.
Yes, but Werebears aren't bears. They were designed to be amongst the greatest hunters on Nirn and so just like Werewolves are superior to wolves, Werebears probably much more powerful and faster than actual bears. Werebears should be slower than Werewolves but still much faster than any normal humanoid. I think the key to "balance" is its stamina consumption and regeneration.
If we had Hircine's realm, we could have all the known Lycanthropes. Technically, nothing's stopping people with the afflictions from traversing throughout Tamriel, so a wereshark or werevulture in Skyrim isn't lore-breaking (in fact, a book mentions that the werevulutres are beginning to show up in Cyrodiil), they just aren't very common in areas the diseases aren't native to.
I agree and I have put forth the notion that Skyrim has the perfect opportunity to reintroduce the Wereboar. It's not a sretch of the imagination to say that someone who just so happens to be a Wereboar crosses the border or moves from Hammerfel to Skyrim. If the book "Lycanthropic Legends of Skyrim" is accurate, which I believe it is, then the "magical barriers" preventing Werebeast from moving is gone. It is also no secret that Vampires infected by different clans travel around. I also suspect that Mjoll the Lioness is a Werelion and was infected during her travels.
There are creatures like special type of gazelles and cattle. I am sure there are other creatures like a weredaedroth, etc.
No confirmation on weresharks/werevultures/werelions/wereboars/werecrocodiles in the Hunting Grounds. But we can be sure some of them exist. Werevultures exist in lore and have been a menace in Valenwood.
I think that the book "On Lycanthropy" is accurate and most of the Werebeast have been either confirmed to exist or are mentioned in one or more sources that suggest that they are more than myth. It makes sence that they would all be found in the Hunting Grounds, Hircine is the "Father of Manbeast" afterall, not just the Father of Werewolves. I think he created the multiple creatures to represent or to have a part in various aspects of the hunt which goes beyond forest. Sharks in the seas, Vultures in the air, etc. The hunt takes many forms and so I have no doubt that the Hunting Grounds possess more than one environment for the hunting or prey. I'm sure Hircine doesn't just give up when his Argonian prey jumps into the water.