Answer:
Two bodies have I, though both joined in one. The more still I stand, the quicker I run.
Two in a whole and four in a pair. And six in a trio you see. And eight's a quartet but what you must get. Is the name that fits just one of me?
People are hired to get rid of me. I'm often hiding under your bed. In time I'll always return you see. Bite me and you're surely dead.
You’ll have me at night and if you remove the first letter I denote the top, such as on a train
I am a box that holds keys without locks, yet they can unlock your soul.
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.