May be too late but...
Musicwise - Vinyl Exchange/Eastern Block/Picadilly Records all right next to each other in Northern Quarter. And Magma also next door for interesting art and design books/magazines.
Exhibitions - Rafael Lozano-Hemmer at Manchester Art Gallery quite good, Goya prints there also well worth calling in for. The Land / Between Us at Whitworth Art Gallery recommended.
Hot Drinks/Lunch - Oaklahoma in Northern Quarter is the best I reckon.