I have attended a few lectures and this question was raised and the scholars all said its fine to wish someone of other faiths a good day etc, its just that we as Muslims dont celebrate those occasions, but nothing wrong in wishing them all the best.

My family is Christian, and i dont celebrate Christmas, as in the sprituality of it, but i do join them for dinner and even make halal dishes for everyone to enjoy.

They give me presents although know i am Muslim, we are allowed to accept them, but i dont give presents to them on acutal Christmas, but we do give gifts in general, due to the hadith about Muslims encouraged to give gifts to family/friends.

As for bdays, very controversial as no Prophets (peace be upon them all) celebrated their bdays, so why should we? It is not part of actual Islam, but some scholars agains say, ok u can celebrate bday, just dont say its a part of Islam, and others down right say, avoid it.

A great place to view answers to such questions (and its moderate site by qualified scholars) is IslamOnline.net- Home - Islam, Muslim, News, Shari`ah, Society, Family, Culture, Arts, Science

They have answers to all your above questions including about dancing and music.