If the topic is still relevant, I would like to answer.
(I am from Russia. My native language is Russian)
1) To unfamiliar persons or bosses we say:
Çäðàâñòâóéòå ['zdrastvujtɪ] (zdrastvujti) or
['zdrastɪ] (zdrasti) - Hello;
Äîáðûé äåíü ['dobrɨj 'dʲenʲ] (dobrij djen') - Good day;
Äîáðîå óòðî ['dobroje 'utro] (dobroje utro) - Good morning;
Äîáðûé âå÷åð ['dobrɨj 'vʲetɕer] (dobrij vecher) - Good evening.
To relatives, friends, and so on we say:
Ïðèâåò [prɪ'vʲet] (privjet) - Hi;
Çäîðîâî [zda'rova] (zdarova) - Cheerio.
Çäðàâñòâóé ['zdrastvuj] (zdrastvuj) - Hello;
Sometimes girls kiss, but it is not so frequently occured.
Boys and men usually shake hands.
Sometimes man may kiss woman's hand, but it is not a rule.
Sometimes the persons, who know each other well enough, may hug.
And, of course, relatives may hug, kiss as well as shake hands.
2) Yes, I have been to Armenia and China.
In Armenia I said "hello" as
բարեվ ձեզ (barev dzez) or just
բարեվ (barev) to familiar persons.
In China - usually as
你好 (nǐ hǎo), but in official atmosphere -
您好 (nín hǎo).
And when I was talking to somebody in English, I usually used to say "hi". But if I met a person for the first time, I prefered to say "hello", "good evening" and so on.
3) Above I have already said about kisses. As I understand, there is such a tradition, you talked about, in France. Each tradition has its background, so it should not shock anyone. Anyway, I was not shocked, when I knew this.
4) I think yes.
5) Actually, there cannot be an international code for greetings all over the world. Also because of those very traditions. I respect traditions, so I would not be in favour of this idea. I like much more, when people can express their ideas in such a way that is suitable and usual for them.