for the purpose is a set phrase, like this,Originally Posted by HelpMe
Question: For what purpose do people usually wear clothes?
Answer: For purposes of warmth and decoration.
becuase of is also a set phrase, like this,
Question: Why do people usually wear clothes?
Answer: Because of warmth and decoration.
We can't mixed the two together like this,
People usually wear clothes because of two basic purposes: warmth and decoration. (ungrammatical: "because of" should be "for two basic purposes".
People usually wear clothes for two basic purposes: warmth and decoration. (grammatical) :D
I'll let someone else help with No.2.
All the best,
- For Teachers