What Am I Riddles

Question: When warm my house expands and when cold it contracts,
I am vital to a certain type of pact.

What am I?

Question: I have curly hair I am a feline I am long I My eyes are shaped like a line. What am I?

Question: You wait for it. It appears, cracks, stays for a moment, then disappears before your eyes.

Question: People pick me, and watch me until they give me power. Then they don't stare in my eyes. What am I?

Question: Once you are in my sight, you are gone in a flash, and people tend to use me for cash. I am often used as a dire assist, and people often believe that I cause harm, when I am but its catalyst. What am I?