Music can be a good or bad thing, depending on the listener... "beauty is in the eyes of the beholder" but in musical terms. If there is slow music being played that I don't like, then I will not want to browse around the store, I'll want to leave as quickly as possible. Sometimes the most important factor for me is the volume of the music. Even if a song is playing that I don't like, if it is playing very quietly over the speakers in the store, then that is okay. If the music is loud, even if it happens to be a song I like, that loud music might turn me off, especially when I'm trying to shop because loud music can be distracting.
Oh God yes. I won't go into a name brand store if it has shitty music on. Respect yourself, bro, you got a tone of profit coming your way. I don't care that much about lower dollar store though, it could be NPR for all I care. I don't have the same expectations of lower budget stores than I do of the higher budget ones.
For me, the music makes me more comfortable, and I usually spend more time browsing in the store. Quite naturally, if I don't have the money at the time, it won't affect my spending. Still, when I take my time in a store, I tend to find more and discover bargains that I end up purchasing, either at the time, or I come back to get them. I definitely notice the music, because I am a music lover.
Music doesn't really influence me when I shop with the exception being extremely loud or annoying music. I'm not annoyed by most genres but there are some that just annoy the hell out of me and I just leave the store right away. There have been some studies that show how music affects gambling in casinos. I think the same concepts would apply in stores. Would be interesting if someone did a study on that.