Nouns

The word 'one' is a noun, an adjective, and an indefinite pronoun. Example uses:

Noun: I only need one, you can have the other one.

Adjective: I can be there in one hour.

Pronoun: One of my students gave me a flower this morning.

Foreclosure is the noun variant for foreclose.

It can be, but is more usually a pronoun or an adjective meaning a large but non-specific number.

The word brave is a noun; brave is also and adjective (brave, braver, bravest) and a verb (brave, braves, braving, braved). Examples:

Noun: The brave are not those who aren't afraid, the are the ones who are afraid and do it anyway.

Adjective: The brave man jumped into the freezing river to pull the dog to safety.

Verb: You can brave one evening with my parents, they only come to town once a year.

Yes, "news" is a thing, and therefore a noun.

The word experience is a noun. The plural is experiences.

The noun improvement can be a subject noun or an object noun; for example:

Subject: An improvement is needed in your study habits.

Object: That was an improvement.

Yes the word system is a noun. The plural form is systems.

Yes.

The word 'enjoyment' is an abstract noun as a word for pleasure that you get from an activity or experience; a word for an emotion.

It is an abstract noun.

Yes, the word 'wonderland' is a noun; a word for a place that is filled with things that are beautiful, impressive, or surprising.

Is undergone an abstract noun