hello, i hope these might help
most of the bands who join the battle of the bands must be seeking some popularity to take a big step in their band, so i think supports from people of different genres of songs are so important,
in an event, its fun to include different genres of songs
as for venue, a cool, huge indoor hall would do just great
other than that, you could set up some booths outside the hall,
this could attract more people to come.
clothings line could rent some of your booth,
as for prize, oh well, who wouldnt want some cash right? lol
and as for date, any public holiday or weekends would be alright so that everybody could attend