1. Don't take it too hard.

2. Don't take it so hard.
3. Don't take it too seriously.
(Are they all the same? What other expressions can we use instead of #1? Is 'hard' an adverb or an adjective? What is the meaning of 'take' in the sentence?)

All three are fine, and they mean approximately the same thing.

In these sentences, yes, "hard" is being used as an adverb.

The verb "take" is one of the most-often-used-in-idioms in English:
http://www.eslcafe.com/idioms/
>> http://www.eslcafe.com/idioms/id-t.html
In other words, it's hard to come up with a definition for it!
http://www.answers.com/take
39 definitions for this verb!!

"Don't take it too hard" = don't be upset

They are all correct. They all are talking about a disappointment. The speaker is trying to comfort the other person.

Hard is an adverb modifying take in these sentences.

This is the definition of take in this context.

"11.to receive, react, or respond to in a specified manner: Although she kept calm, she took his death hard."

from Dictionary.com.

yes

1. "Don't take it too hard" means not to be too upset or affected by something. In this sentence, "hard" is an adverb modifying the verb "take." It emphasizes the intensity or severity of the action.

2. "Don't take it so hard" is very similar to the first expression and conveys the same meaning. The word "so" in this case functions as an adverb of degree, modifying "hard" to indicate intensity.

3. "Don't take it too seriously" is another expression that conveys a similar meaning. It implies not to give too much importance or significance to something. In this sentence, "seriously" is an adverb modifying the verb "take." It emphasizes the attitude or approach towards the action.

Other expressions that convey a similar meaning include:
- Don't let it get to you.
- Don't dwell on it.
- Don't be too affected by it.

To understand the meaning and usage of expressions like these, it can be helpful to consult a dictionary or online resources. A good resource to use is the Merriam-Webster dictionary website, which provides definitions, example sentences, and possible synonyms for various words and phrases. Simply searching for the expression or the individual words within it can help clarify their meaning and usage.