Plural and Singular confusion problem and some others..

Hi, I learned English long enough to teach others. But these days, I'm loosing my confidence in English. There's this problem I have and please help me to go through. Thank you.

Here's the question: is it right to say "Werewolves are wolves with a human body" OR "Werewolves are woves with human bodies"? is it "a human body" or "human bodies" in this situation?

Oh two more, "I am under a pressure" OR "I am under pressure" which is correct?

Next one is really easy, is it right to say "Do you have car" OR "Do you have a car"? and "Can you find a fan here?" OR "Can you find fan here?"

Thank you very much, and I'll post up some more questions later on. Thank you for your concern again.