Answer is conjunctions. Adjectives describe something and nouns are a person place or thing.
Answer: by giving examples of countries that have become democracies.
I most contexts, no. It can be considered an error if viewed from a programmer's perspective, because a bug is viewed as an error in the code of a program. If it is not viewed from a similar perspective, then it is not a synonym. Thesaurus.com can be a helpful place for you.