Could you please give me some help with "usage" and the noun form of "use"?

What is the difference between them?

Can I change "use" to "usage" in the following sentences?

A ban was imposed on the use of chemical weapons.

The software is designed for use in schools.

I'm not sure that this is the most valuable use of my time.

The ar is for the use of members only.

Could you help correct this sentence?

I'm confused about the usage of 'usage'.

Thanks in advance,

You cannot replace 'use' in any of those sentences.

Usage: accepted or habitual practice. Usage refers to an accepted standard for a group that regulates individual behavior (from the American Heritage Dictionary).
ChristanfordCould you help correct this sentence?

I'm confused about the usage of 'usage'. This might be the one example in which "use" and "usage" may be interchanged. Emotion: big smile

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Thanks guys!
I always thought those words could be used synonymously as nouns (when 'usage' doesn't refer to a habit). From Dictionary.reference.com:

    1. The act, manner, or amount of using; use: the usage of a technical term; an instrument that measures water usage. 


    1. The manner of using; usage: learned the proper use of power tools.

    The American Heritage® Dictionary of the English Language, Fourth Edition

    According to Wiktionary, the words are synonyms.

OK, Abraxas, let me say this about that:

Frankly, I find the Dict.ref examples of 'usage' a little stilted at best. 'Use' would be better in both cases: the use of a technical term; an instrument that measures water use. This in spite of the fact that I normally rely upon the American Heritage series for confirmation. (I presume from your post that Dict.ref is referencing Am Heritage for those examples.)

As for Wiktionary, I suggest that you avoid that site, along with Wikipedia, as a primary reference. Both are built by an anonymous committee of no reputation whatsoever.

Nevertheless, I am willing to bow to any BrE speakers who recognize a different usage than seems natural to me.
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Abraxas25 the usage of a technical term;
To my ear (etc.) this phrase is an example in which "use" may clearly be substituted for "usage"; but the meaning changes. (I'm not sure if this has been addressed.)
In my earlier post, I didn't mean to imply that the meanings were the same, although it could certainly be taken that way.Emotion: embarrassed