So... this is a new dimension called "the Cave" that you are proposing... like the Nether and the End that is separate from the main Overworld?
Rather than just listing a bunch on new block and MOB ideas, can you provide a general overview of what you are envisioning for this realm?
For this to not be a Wishlist, all these ideas have to be tightly and directly related to each other, plus there should be a detailed explanation of each proposition that other forum readers can respond to, critique, suggest changes, point out pitfalls, etc.
If you are just going to list a bunch of thing you want without relating them or backing up your reasoning, then that makes it a wish list, and you may as well just post that in the 'Small Suggestions' section rather than devoting a whole thread to discuss a multitude of separate ideas: Small Xbox 360 Edition Suggestions
The general philosophy here is that if each idea has merit worth discussing, then they are deserving of their own thread to discuss that particular idea. Also, many of these things on your list have been proposed in the past, and it is better to add to those threads, than it is to make numerous separate threads that say pretty much the same thing.
Please do not create wishlists. If you have more then one feature you wish to suggest, please make seperate threads for each idea. If it is a small suggest, please use the thread listed above by GregNelson.