It means you like or love something so much you lose your perspective or objectivity about it such as "He was head over heals in love with her". Idioms in normal conversation can emphasize the subject matter quickly.

Both answers are correct. There are people I know who barely go more than a sentence without using some kind of idiom. It is less common in formal writing, and stylistically you see those phrases surrounded by quotation marks in what we idiomatically call "scare quotes" (like that) these days in the US as a way of making it perfectly clear that it wasn't the speaker's choice of words. (P.S. it's head over heels, the back bottom part of your feat, not "heal" or "heals")

If you wish to use idioms in everyday conversation, then you must get them perfectly correct. Any mistakes or paraphrasing will change or destroy the meaning. "Head over heal" is an embarrassing mistake, so make sure you know your idioms before you use them. People do use them in everyday conversation, so of course you should get used to them too.

The idiom is "Head over heals(rather than heal)". It means "To be hopelessly in-love with". Ways it is used: Being in love with someone specific: "I'm head over heals in love with her." or "I'm head over heals for her" The state of being in love: "I'm head over heals right now." Idioms are commonly used in English during conversation. In most cases, they are essentially used as synonyms for what they mean.

It means to love or be in love with someone. Ex: I'm head over heels for him. Ex: Should I tell her that I'm head over heels for her?