Found these charts while looking for some other Hangul related stuff. I haven't had a chance to look over the site is linked to, I will soon but for now I really wanted to share.
@xojuliettexox Someone had asked that same question. He answered that they are not commonly used or not all.
What he wrote: "The grey hangul combinations are combinations that are not commonly used, or not at all. To answer your second question, the reading for every character is written underneath the character, not above. I hope this helps."