Up front, if you want to watch the show go watch it. If you want to shoot it go with a mind to shoot it. You'll have enough 'fun' trying to get the job done. Besides, you'll 'see the show' endlessly while you're editing.
As for the XLR Mini adapter (my bad I had it listed as 3/4" when it's 1/8" or 3.5mm. I got the 'mini' part right though), the 'Law of Averages' clearly states that whatever you get will be the one you don't need! Best bet is to get one of each type of XLR – Mini 3.5mm adapter (1 XLR male and one female. The mini end will be female.) That way you'll have the bases covered. At the minimum get a XLR male to Mini Female. If you're in the States, one will cost about $10. Here's a link:
Concerning your other question 'having all that footage' will make your time editing easier to deal with. If you just want a boring long ass shot of the band on stage that doesn't change, then just set up your camera and let it run. If you want to show how exciting it was to be at the show you'll do like I laid out and get that extra footage. Look at concert videos on the 'Tube (YouTube.) The boring ones just sit there and that's all. The better ones take the viewer to places the people in the audience could not have seen during the show. You want to bring the experience of being there to your viewers. The only way to do that with video is to follow the plan I laid out for you. Good luck!