Prefix -un and suffix -ness

My room is a mess, it isn't tidy. It's ...

I am very bad at playing sports. I am weak. That's my ...

When we add the suffix -ness to a word like happy, we have a new word category. Is it an adjective, a noun or a verb?

The game hasn't got fair rules. It is ...

This condition is good because you can see your things tidy.

When someone is ill, that person has an ...

This state makes you feel happy.

The word "unfriendly" means not ...?

She listens to everyone's problems. She expresses her k...

I like quite rooms. So ... is very important to me.

When we use the prefix -un in a word like "happy", are we changing the word category or does it continue being an adjective?

The opposite of helpful is...

They never smile or say hello. They're very ...(not friendly).

I am writing a sad story. It's main topic is ...