There's plenty of opportunity for new songs in the psalm settings, the offertory and the communion anthem - although our GIRM (General Instructions for the Roman Missal) sets some limits.
My personal opinion is that we Catholics have a treasury of over 800 years of particularly fine music written for the Mass that has passed the test of time, and it should be used more often rather than focusing exclusively on music from the last 10-15 years. There is GREAT stuff to be sung and it reminds us of our continuity.
And dancing is right out for us - although it's fine if you're evangelical or pentecostal because it's part of that tradition. One thing I've found is that the "liturgical dancers" who impose themselves on Episcopal and (heaven forfend) Catholic churches are the ladies who couldn't possibly get a gig anywhere else.