I'm assuming going in this is informal. If that is a correct assumption, most commonly you will hear いつくですか?(ikutsu desuka? ) for "How old are you?"
This is a mess in mostly English....but the protocol is basically the same. You just have to bow at the end in Japan and tell them to say something like "はじめまして。どうぞ宜しくお願いします」
1. To introduce the Japanese person to your friends:
ああ、[Person you're introducing them to], 紹介します。
これは、[Person(s) being introduced] です。
Person being introduced 「*Gives their name again* です」
2. If you want to introduce your friends to the Japanese person:
Japanese friend's name を紹介します。
If this is supposed to be a formal set up, uh that changes things. Get back
with us before trying anything like that on your own.