moonshoes, I've seen it both ways. I've seen Steubenville, etc youth retreats that seem to be both very energetic and very focused on orthodox Catholic teaching and reverence for the Eucharist. I'm also fine with people disagreeing with me, but I feel that they are an excellent example of Pope John Paul II's call to the New Evangelization, using new technology and new methods of meeting our culture where they are and bringing them closer to Christ. It's not just about feelings. It is music that helps certain people to realize and appreciate the significance of what they are given by their Catholic faith.
Contemporary music, including some music that is used in both Catholic and Protestant communities, is also sometimes helpful for people who are in the process of converting. It makes the Mass seem less foreign for those who are attracted to our beliefs. At the same time, I do see that for some people, the contemporary music can be a barrier to reverence or a distraction from the significance of the Mass, more like a party than a sacrifice. I think it depends on how it's done and how the people are responding inwardly to the style of worship. I know from experience that you can't judge that a person is particularly holy just because they are acting very reverently or that they are not particularly devout or reverent just because they look like they're just having a good time.
As far as clothes go, I agree that it important to dress modestly and reverently for Mass, but I think it is more important for people to be there period. Today, for example, I finished up another activity with just enough time to run to daily Mass, and I was wearing jeans and flip-flops, and you can bet I went to Mass in what I was wearing. Normally, I would try to be a little more formal, even for daily Mass, but if I suddenly get the opportunity to make it there at all, I think going to Mass is more important than worrying about what I'm wearing. There are certain things that I think there's no place for (immodest clothing, chewing gum, eating, chattering, etc) because they are just not respectful.
At the same time, I can see what you are talking about with contemporary music sometimes being accompanied by liturgical abuses and beliefs that are contrary to the Magisterium. I see it at my own parish. Thankfully, our clergy is using the opportunity of this new translation to fix many of these liturgical abuses.
I haven't heard anything from any of the parishes I have visited lately about changes to the style of music or introduction of musical settings of the antiphons. It just doesn't seem to be on the radar of anybody I have talked to, and people who I have brought it up with at my parish have gotten defensive and told me that I'm wrong, that we're not being encouraged to make any changes except that we'll say the antiphons after whatever contemporary song we do. The educational materials sent out by my parish didn't even go that far. They claimed that there will be no changes to the music besides the retranslations of the Ordinary of the Mass. All I've heard of it has been online, so it's hard to know what we are actually being asked to do, and I don't expect to see many changes in the music from what people are already doing.
mt_gooseberry, Protestant congregations are not bound by whatever the Vatican requires (Though, make note that these changes are just to the English translation of the Mass. Other languages are not being affected by this change, though I have heard mention that they are considering retranslating the Spanish as well, sometime far in the future.), but Catholics and Protestants do not live in a vacuum. They are more affected by each other's decisions than most people realize. Many people who are against Vatican II will tell you all about the Protestant-based prayers inserted into the Mass after Vatican II, and the readings specified for each Sunday are very similar in the Catholic Church, and Lutheran and Episcopalian congregations. One denomination is not required to accept the changes in liturgy made by another denomination, but some denominations have kept their liturgy very close to the Catholic liturgy despite being separated for centuries. It is no coincidence that my husband's family accidentally went to an Anglican service some years back and didn't realize it until far into the service.