-ize
To add a suffix to "habitat," you would simply attach the suffix to the end of the word. For example, adding the suffix "-ion" would create the word "habitation."
a
One suffix you can add is -en. In this case, the word would be seen.
To add the suffix '-ness' to 'immaterial', you would remove the last 'i' and add 'ness'. The word would become 'immaterialness'.
You would add the suffix -less meaning without or lacking, to make "senseless."
You can add the suffix "ment" to form the word "involvement."
The suffix that you would add to the root word truth in order to create a word that means by honesty is ful.
You could add the suffix -ed to it to make the word hunted.
Care
Legalizing
Sure, if you add the suffix "-ly" to the word "significant," it becomes "significantly."
A common type of suffix that could be added to the word "replace" is "-ment," to form the word "replacement".