I have JUUUUUST the right fics for your second request \o/

First is only one of them playing an instrument, though.
Don't go mistaking paradise (http://users.livejournal.com/__tiana__/71275.html): Jensen loves only two things in his life: drumming and his best friend Jared. Unfortunately, Jared, his head buried in his painting and a years old crush on a girl named Sandy, only knows about the drumming.

Thunderbird Whine (http://senorwences.livejournal.com/2194.html): Summary: Rock & roll J2 AU, which has moments of angst, but it's mostly fun. Jared is a singer, with big time aspirations and a huge crush on the drummer of Thunderbird Wine, Jensen Ackles. Coincidentally, Thunderbird Wine's singer goes off the rails, and the label wants him gone. The band needs someone for 12 shows and an album to fulfill their contract. Think shirtless, sweaty, tights, hair extensions, and living on a bus with a Machiavellian manager, a ferociously cheerful bassist, a lead guitarist who’s more than a little rodeo and the prettiest damn drummer in the industry.