Sam,
1. As I posted Rav Aviner madethe statement about an enjoyment one is compelled to receive. I quoted the Gemara as an example. Othewise Rabbi Hyya bar Abba would have said that the man must cancel his plans and not just praise him for closing his eyes.
2.Who says that aiva doies not apply to Jews? As for pikuach nefesh, there is a mitzva to go into the Army to defend the country and its people as set forth in Rambam Hilchot Melachim.
3. The Seridei Esh speaks about zemirot, song in praise of Hashem, etc. The Sede Chemed in the name of theDivrei Chefetz talks about kinot. Rabbi Bleich discusses this in his article.
4. It could be that sevral heterim are needed and I listed several.
5. That is not the way secular people think. Professional singers especially consider this an expresssion of their whole beings.How would you feel if someone would get up and leave when you started to speak knowing that it is because he disagrees with you? In any case, it is not my statement but that of Rav Yosef Carmel of EWretz Chemda. If you want to argue with him, send him an e-mail at http://eretzhemdah.org/contactus.asp?PageId=10.
6. See this statement by Rav Metzger at this site (http://www.theyeshivaworld.com/news/General+News/113890/Rabbi-Metzger-Comments-On-Resignation-Of-Air-Force-Rav-Ravaad.html):
Chief rabbis over the generations took part in state ceremonies, which to my sorrow included kol isha. This includes Rabbi Ovadia Yosef. They did not walk out in protest. They found their own personal solution, perhaps to concentrate on learning or something else. When I was a soldier for example I did walk out but I was not chief rabbi then.
If Rav Ovadia did not feel required to leave what can we say?