"health food" or "healthy food"? Can we say "health food" or "healthy food"? Are they all correct?

"Do you get it?" or "Did you get it?” I ask some kids to guess something. When I show the answer, should I say "Do you get it?" or "Did you get it?”? Or I should say another sentence? Please help me. And many thanks.

"I love apple." or "I love apples." Can I say "I love apple."? Cause I heard some guy sing like that, But I think it should be "I love apples." I'm really confused. So I come here and ask for your help. Which is the right one? Or both OK? Many thanks^_^

About the sentence "My job is on the way." Can I use the sentence "My job is on the way." to express that "I'm going to get a job."? Thanks a lot!

About the sentence "I'll fix you up." I'm confused about the sentence "I'll fix you up." What kind of situation does it use in? Does it mean "I'll help you to make the bed, sweep the floor and so on"? Does it mean that I'll recommend a job for you? Thank you very much!

About the sentence "I fired my boss." Can I use the sentence "I fired my boss." to say that I quitted my job? And is it pure English? Thanks for your helping.

What's "Get your head together." mean? A friend of mine told me that he was going to change jobs. Can I use this sentence "Get your head together."? Does it mean "think over"? And is it often used in our daily life? Thanks a lot!

What's the meaning of "put yourself in my shoes"? Who can tell me? Thanks a lot! I wanna know the meaning of "put yourself in my shoes". Hope you can help me!O(∩_∩)O~

Who can tell me the meaning of "take a beat"? Thanks a lot! There are some lines of "The Vampire Diary" . Katherine: I'm just a girl looking for a partner in crime. Feel like hitting the road? Getting the hell out of dodge? Damon: Impeccable timing. I was told I need to take a beat. Katherine: Is that a yes? I'll drive. I don't get the phrase "take a beat". Who can help me explain it? Thanks!