Answer:
I begin your sentences.
I am a popular afterlife location to send evil people
Take off my skin I won't cry but you will.
What kind of dog keeps the best time?
I stand in one place yet fill the whole room. I can be filled with molten rock and come in every hue. What am I?
A mysterious, fantastic creature, It has one defining feature, And for humans at their worst, In their eyes it's just a horse