Honestly, I believe you can find most of the answers here on this website. There are areas that talk about dance moves and go through written detail. As I am sure you are aware, there are also weekly variations of steps, which have video clips. As for the people that dance the style now, I have to say it is any age range. The studio I go to has a young man that is ten years old taking lessons and there are people I believe to be in their 70s taking lessons. I am not so rude as to ask their age. You could check out things on Dancesport to try and find ideas of the costumes used for competitions. I have done searches using ballgowns or ballroom dresses which has taken me to great sites. As for type of music, ballroom dancers.com has a music section in their store. You can hear a few clips of the songs too. The reason I mention all of this being on the site, as you probably already know, the questions cover a broad range of things. It would be easier for you to browse and find what you need.
I hope this helps. And good luck on the project.