a
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."
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'.
-ize
You would add the suffix -less meaning without or lacking, to make "senseless."
The suffix that you would add to the root word truth in order to create a word that means by honesty is ful.
You can add the suffix "ment" to form the word "involvement."
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".