I haven't played in it, but I would like to in the future
Despites the costumes you mentioned, the music is kick ass!
If you want to develope yourself for that kind of music, you should get a 5 or 6 string bass. This way you have more range for your bass lines. When it comes to your techniques, I would recommend Franck Hermanny's bass licks DVD.
Franck Hermanny is the bass player of Adagio, a Progressive Symphonic Metal band. They started as a Neo-classic Metal band, but got more in the Symphonic Metal and Death Metal with there later albums.
His DVD doesn't only teaches you the awesome bass lines of Adagio, but you will learn tapping (2 hands), bass sweeping, double thumbing, alternative thumb picking, slap 'n pop and flamengo-like strumming.
However, Franck plays 6 string basses exclusively and use the range of all 6 strings a lot in his work. So if you would like to buy his DVD, a 6 string bass is the best to have