Look after the guy in your band that sorts out the money, deals with agents and contracts. This is a thankless task and the time and effort involved is seldom understood or apprecaited. Just doing the music, irrespective of going the extra mile is no compensation. We all play through choice but few sign up for the grief and hassle associated with punters who like to take their own prejudices and insecurities and make them our problem.
I'm not sure I agree with changing up cover material though. I tend to think cover bands are booked to play popular tunes. Typically these can be cheesy ballads or disco tunes you might not choose to play. In my experience people want to hear authentic versions with practiced endings, this tends to mark out the higher paid acts from the pub bands. Consider the point that most major hits are played by very accomplished musicians so this authenticity rather than a kop out is actually quite demanding. I suggest this is why so many cover bands fail to make the grade. Remember that in addition to the music you are the focal point of the evening so you need to collectively engage the crowd and break down their inhibitions. If no one in the band does this naturally then you will need to contrive an approach. I know this sounds corny but I'm sure it is necessary.
Good luck with it