I disagree with number 3.
If I like the band, I probably have their albums at home.
I want some variation on the themes.
These days I would think if it sounds like the album, they're probably lip-syncing.
Of course it's been ages since I've gone to concerts. Late '60s-late'70s though I went to all that I could. That was the thing to do and I saw a lot of great bands.
On opening acts: Sometime early in that haze I went to see Black Oak Arkansas. The opener was some band I hadn't heard of called Montrose.
Ronnie and Sammy and Co. put on one of the best shows ever!!! I think they did about fifteen minutes of "Bad Motor Scooter"

.
Mostly Ronnie Montrose's guitar work
BOA sucked, having to follow them.