I think it best to ask the club manager what to do for breaks..... then if it backfires, it's not your fault!!

Ditto for length of set (linked to pay, of course!).

Personally, I prefer to put CDs on myself during the break, firstly, you've probably got a better sound system than the house, and secondly, you can shape the evening's energy to better fit with what you are doing....... If you are packing the floor for 50 min, you might want to let them relax a bit and go to the bar, if you are playing mostly 70's and older songs to a younger crowd, you can give them a little hiphop to grind to....... I just find it is better to contrast what YOU do a little, so when you go back to playing, their ears perk up.