Yes, you would need to ask permission from the band - you get it by contacting their manager or the band itself and talk about it. Anyway, if you are writing a docu-biographical screenplay, you would need to interview the band members themselves and their family for an accurate data - websites such as wikipedia will not give you the best info.
No. You can change names all you want and even change the band names, as long as the story is same with another band, you can still get in trouble. You would need to change a whole lot and making it more like "inspired by" than based on.
